Ps3 – Got a Playstation Classic (PS1) and Games list shows two icons for it, is it safe to delete one

The PlayStation 3 (and Vita and PSP) utilizes the PlayStation Store, which is similar to the Xbox LIVE Marketplace: you can purchase games digitally and do all that stuff. It doesn't have as large of an indie gaming scene as Xbox LIVE as there is no XNA equivalent for PlayStation development.

Most, if not all, retail-purchased games will require the disc to play, but many games will install at least some of their assets onto the hard drive for performance reasons. How much they install depends on the game: there is no standardized system like Xbox has.

If you purchase a membership to PlayStation Plus (somewhat similar to Xbox LIVE Gold, except you don't need it to play multiplayer or use add-on services like Netflix: it's more of a value-add service), you get 150 MB of backup space. Some games support backing up to it automatically, but you can generally place any saves you want there manually if need be.

You've over complicated this.

For PS3, basically once a DLC was installed on a system, any user on that system can play that DLC and earn trophies for it, whether signed in to PSN or not, I've never seen DLC which is only usable by the buying user except for items like Home items, Avatars and DLC for one specific game I know of.

So your "process" is fairly simple:

1. Log into the appropriate store for your game's region (you'll need another PS3 profile with a PSN account in that region)
2. Buy DLC from that store (funds could be from a local credit card or prepaid PSN card) and install it.
3. Log back into your main profile and account and play the DLC.

PSVita is different. A PSVita system and memory card is locked to a single user, so even if you switched the Vita's user (system restore), you'd still be only able to download the DLC to a memory card assigned to the "foreign user", meaning it won't be accessible to your "main user" (which will need its own memory card), this means that in order to buy DLC for a PSVita game, you must own a copy of the game from the same region as your main PSN user. There's no current way to avoid this (at least one that I know of), and it basically means any PSVita game that has "required DLC" like online passes, UPlay pass, etc, will only be "fully playable" if you buy games from your own region.