All my answers come from the perspective of a novice, fairly new modder. I've built several player homes, and a few minor tweak mods for personal use. Most I haven't released, but I recently did my first full blown quest mod (see my sig) that's being well received thus far. But keep in mind there are thousands out there with MUCH more experienced than me. I feel like I'm basically hacking my stuff together with duct tape and chicken wire at times so I can relate to your questions and concerns.
Q - Is it difficult to learn how to mod?
A - Yes and no, and it really depends on what you're trying to build or accomplish. For me, the actual building process of snapping together kit pieces, adding clutter and decorations was extremely easy. In fact, it's what I enjoy the most because you get to see your creation come to life a little at a time as you're building it. And I always get a great deal of satisfaction starting from a blank canvas (if you will) and watching it unfold as you go along. I was just blown away when I finished my Casino & Steak House. Part of me still can't believe that I really created something that detailed and beautiful. (It's beautiful to me at least, and others have said it is to them as well.)
On the other hand, scripting, quest conditions and things like that are extremely difficult for me as I've never had any scripting experience. And for me, those are the least enjoyable and most tedious part of modding. But, I have talked to other modders who are the exact opposite of me and loathe the building process but love making quests and scripting.
So I think the ease at which you learn could possibly relate directly to what you personally find the most fun or satisfying.
Q - Is it a long learning process? Like a year or so of constant trial and error?
A - No, not at all, at least for the basics.
Q - would you guys say its rather the same as learning html?
A - There are definitely things about scripting that knowing a little html really helped me understand. But scripting is nothing like html at all. But what helped me was being able to look through the code and find the bits that were doing certain things, and be able to understand a little about what I needed to find and edit to fit my situation. So in the way you can pick through html and find where a table or image might be inserted and edit that to what you want there is a little similarity, but nothing more really.
Q - there seem to be basic walk-throughs for modding oblivion. Will there be the same for skyrim or will there be a wait for that because of the new engine?
A - I would imagine so at some point, but it might be a little while for those to come out would be my guess.
Q - is it presumed that modding skyrim will be akin to modding Oblivion? like if you know how to mod oblivion you will mostly know how to mod skyrim? or is everyone going to start from scratch and everyone will be on the same learning curve when skyrim comes out?
A - It depends on how much the Construction Kit has changed. I'm not sure anyone knows for sure right now. We'll just have to see I guess. But my personal feeling is that since it's the same engine (just updated) I would be surprised if it's not at least somewhat similar to the GECK and CK. (But I could be totally wrong.)
Q - Will you need a more powerful computer to mod the game than just to play the game? or is that dependant on the mod you do?
A - If you can play it you should be able to mod it, but as much RAM as you can get helps as with anything.
Q - if i were to have a computer and downloaded someones mod would i be able to look at it and figure out how the person did it?
A - Most likely if you dig deep enough and know what to look for.
Q - do you have fun playing your own mods? Like making a new quest and going through it? or is the fun taken away since you already know everything about said quest and make the quest for other people to enjoy?
A - It's fun playing my own mods, but in a different way than someone elses. Yes, you know what is going to happen, but what's fun for me is when your mod all comes together, works perfectly as you intended it to. There's just a feeling of satisfaction and knowing how many hours, heart and soul you put into it and finally it all works like you intended it to. There's really nothing like it!
sorry for all the questions... and thanks for any answers i get.
Finally, remember “Aim small, miss small”! In other words, don't try to create some huge expansion with your first mod. Start with something simple like a player home or random interior. Learn the basics and start working up from there. Get an interior up and working, and make a little 2 or 3 stage quest for it using simple scripts, notes, keys or other objects. Create a new vendor or NPC and learn AI packages and dialog. Then just progress at your own rate! Most of all, have fun, and post in the forums here for help if you get stuck. But be warned, you will not likely get a lot of help if you don't put in a lot of work and effort to try to learn on your own. I've been told before, “This is not school”. But there are a lot of folks who can and will help if you put in your part of the effort!
Good luck and if I can help you let me know!