When I do a clone - after mounting that partition, I quit all apps and cease all activity until the clone is completed. I usually also Stop TM in Sys Pref before starting the cloning.
You cannot cease all activity. OS X is always updating an astonishing amount of stuff in the background.
I learned this back in the days when I used Retrospect to do my backups. For all its faults, Retrospect had one very nice feature: after calculating what files had changed since the last backup and copying them to the backup, it went back and compared original vs. copy of every file it had copied, and report as copy errors any that did not match. I was appalled at how many files were repeatedly on that list. Not because they were actual mis-copies, but because OS X is constantly updating them even when you think nothing is going on.
I could exclude some of those files from backup, but there were many (my Address Book database, for example) that I really wanted backed up. To get a clean backup, I had to disconnect from the internet and go into half a dozen different applications and temporarily disable features. Then I had to remember to re-enable all those features after the backup. (I cannot remember what feature I had to turn off in Address Book (now called Contacts), but it's normally updating its data every half hour or so even when it's not running. The copy phase of a Retrospect backup took longer than a half hour, so it was always catching this as an improperly backed up file.
The file updates that OS X does in the background are mostly limited to files on the boot volume (Software Update being the main exception now) or to files that don't get cloned anyway (Spotlight index, for example). I finally worked out that the only way to get a clean Retrospect backup was to be booted off a different volume than the one I was trying to back up. (But then, to get a backup of that different volume, I had to have a different Retrospect backup set just for it.)
You absolutely should not be actively using your computer while cloning your boot volume. Odds are, that's enough. It's unlikely that a miscopy caused by copying a file that's being updated in the background is going to bite you. I don't like gambling with my backups, though. I never clone my current boot volume.
it would make sense that upon completion of the most recent backup, the (2d) TM would be capable of a full restore based upon the state of the computer at the time it was made. Is that correct?
Yes. Each Time Machine snapshot is complete as of the time it's made. You can use any TM snapshot (including the latest) to restore to exactly the state you were in when TM made the snapshot.
...I've actually never done a full restore from a TM (other than using my TM in the update process going from Mountain Lion to Mavericks); in previous emergencies, I've successfully restored from a most recent clone.
A full-disk TM restore is essentially the same experience as when you used Migration Assistant to restore your data from TM. You boot off any other volume (Recovery HD will work, as will the copy of it that TM made on the backup volume.) Use the menu option to restore from TM, and the system will walk you through the steps. The procedure was well thought out. TM will tell you what information it's going to need from you (which backup volume, which snapshot on that volume, which volume you're going to restore onto), then it collects that data, then it reminds you exactly what it's going to do (including the fact that it's going to erase the volume you're restoring onto), and waits for your final OK. Once you give the OK, you can walk away until it's done. Your files will be restored at full disk copy speed. When it's done, it'll ask one final question: do you want to now boot into the volume you just restored?
A follow-up about cloning and in regards to the name of the clone... Say, one's internal drive is named MBP HD, and cloud based syncing, between devices, is being used (say, using Dropbox for 1Password) for specific apps. Additionally say, one names the clone as - MBP HD 2; and then, a clone restore is completed to the internal drive. Must all sync paths, for apps using sync, be manually renamed to correspond to the original, named path; or post clone-restore, will the respective app-syncs on the newly re-cloned internal drive work fine without intervention other than simple renaming the clone-restored HD back to the original name (in this case, MBP HD)?
As a general rule, you do not need to update any paths. Apps remember where key files (including files they sync) are in one of three ways: as POSIX paths, as HFS paths, or using aliases. (Symbolic links are based on POSIX paths.) All of these can be either relative or absolute. The relative paths will take care of themselves; they'll be relative to something found one of the first three ways. POSIX paths pointing to files/folders on the boot volume refer to it as "/", so the name of the boot volume never shows up.
HFS paths and aliases do contain the volume name (assuming they're absolute), even if the target is on the boot volume. Some backup software will update aliases based on the boot volume so that their copies will be aliases based on the clone. But they can only catch the aliases stored in alias files. Aliases and HFS paths stored in preference files and such-like won't get caught, and will still point back to the original disk.
But when you clone again to restore your original disk, and give it the original name, it all comes out right. Aliases that were updated during the original clone will be updated again during the restore. Either way, anything that pointed to the original disk will now point to its restored copy.
One way you can get into trouble is if, when you restore, you don't give the restored disk the same name it had before. Absolute HFS paths and absolute aliases won't find the restored disk. (That is, if you back up by cloning "MBP HD" to "MBP HD 2", and then restore by cloning "MBP HD 2" to "Restored MPB HD", you may find apps still looking for "MBP HD" and not finding it. You should restore by cloning "MBP HD 2" back to a possibly reformatted disk "MPB HD".)
The other way you can get into trouble is by booting off the clone. Some apps will find the files they want to update on the "boot volume" (or relative to something on it, like your home folder), which is now "MBP HD 2", but others will continue looking for and updating them on "MBP HD", because they use absolute HFS paths or aliases. When you later restore by cloning "MBP HD 2" back to "MBP HD", all those changes will be lost. This is another reason why I advise never to boot off your clone (except maybe once to verify your backup procedure, but you should then consider that backup suspect, and make another).