Qs: (1) Easy to install MODS? (2) Upgrading (3) Mod check

[spark911]

(1) I guess it depends on mod to mod, as some people will give great detailed instructions and others wont - but if we assume I know nothing about coding, but am capeable of following instructions of what to put where, how easy is it to install the MODS?

Also, how easy is it to revert back if it all dies!

(2) When a new version comes out, how easy is it to upgrade if you've got lots of hacks/mods. Do you lose these modifictations when you upgrade? Or do some/most stay regardless of the upgrade?

And is there some automatic install for the upgrade?

(3) I was wondering if this MOD existed.
Lets say I have a forum with 3 main sections.

{A}
{B}
{C}

And users are unlikely to want to post in more than one section (as it'll esentially be a repeat but forcused at people from different countries). Is there a mod so that I can allow people to pick the organisation/order of the forums?

e.g:

If I only ever wanted to post in section {c} as it's about my country, I would find it annoying to have to scroll all the way down past {a} and {b}, so for those who select {c} can I allow them to see {c} at the top - while others see it at the bottom?

As well as order, I'd like to minimise the forums - so instead of listing big forums that aren't related to you, I'd like to minimise them into 'forum groups' which will provide links if people wanted to still look at them or post in them - but as most people wont then it wont be there in the way.

Does such a mod already exist?