Whilst playing version 1.2.0416 vanilla I ran into a bit of a dilemma during the last thieves guild quest. It's time consuming and requires you to cover a considerable amount of long, winding dungeon corridors, during which you run into quite a few enemies. I've retrieved the scroll and fallen to safety but the problem is now with looting. I've had to leave behind a ton of armor and weapons begrudgingly that will probably take God knows how long to completely run back to the surface again without a strength cheat that would allow me to take it all in one go. Is it safe to use:


a. the "modpca" cheat temporarily? I did so and now have a saved game before and after the looting and am not sure whether to go back and do all the looting manually to avoid future problems. Strangely, I engaged in combat while my strength was super-high and didn't do any additional damage...I was also surprisingly slow (maybe due to being encumbered, even though I had the fake strength to hold all the loot?)
b. the "modpcs" cheat temporarily? It triggered the leveling dialogue and I'm concerned that might screw something up down the road.
c. the "unlock" cheat on the door that you initially open with the arrow of extraction? I wasn't sure if there's a way to go back twice normally. If so, let me know. There's some decent stuff that I missed due to trying to escape undetected. Oddly, when I returned to that level one of the guardians (the only one that chased me) that I had killed now stood upright again - perhaps a sign of a glitch or nothing to be worried about?

Thank you.

If you want a temporary change to your attirbutes and/or stats, use SetAV AttributeName/StatName Desired Level. (Example: SetAV Strength 500). Modpcs and Modpca act as skill increases (i.e. they will increase your level).
In the future, consider using mods like http://tesnexus.com/downloads/file.php?id=4065 or http://tesnexus.com/downloads/file.php?id=27918 so you don't have to worry about encumbrance.

As stated above, the SetAV command would work better, as you can reverse that without it having done anything towards your leveling. TGM also works, it disables Encumbrance. But at the same time, it is god mode. Or, one of the fine mods Vyper linked work too.

Can mods be added at any time? Thanks for the info. Any thoughts on the other issues?

There are a small handful of mods out there that need to be installed and running at the beginning of a game (an alternate beginnings mod would be one example). But nearly all mods can safely be loaded after you have begun your game.