I'm going to get a computer soon, and when I'm through with Morrowind, I want to play some Arena and/or Daggerfall. I just had some questions on the two games.
1. Is it worth it?
2. I've heard they are really buggy and prone to crashing. Is there any way I can stop or reduce these occurences?
3. I've played Oblivion/Skyrim first. Does that mean I can't fully enjoy Arena/Daggerfall?
4. Are there mods for the two games?
5. I've heard of this DaggerfallXL. What is it? What does it do exactly?
6. Which is better to play first: Arena or Daggerfall?
7. Daggerfall is SOOO big! Will it take forever to play through?
8. Any gameplay tips for these games?
9. Will a newer computer be able to play these games?
10. Can I download the games?
Thanks for your answers!

1: Sure.

2: Not any buggier than recent Elder Scrolls games =P. The real trouble is occasionally going through walls and getting lost in dungeons in DF. This can easily be solved by pressing alt + f11 a few times usually, which moves you back a few spaces. Also, back up your saves occasionally. It's not common, but a save corruption can be a real pain.

3: Not at all. Just go in with an open mind and you should be fine.

4: There're some, but nothing nearly as extensive as what can be found for Morrowind onwards to my knowledge.

5: There's a topic here: http://www.gamesas.com/topic/1058120-daggerxl-the-continuation-ii/ that will tell you much of what you'd need to know about the project. It's basically a big ol' overhaul.

6: I prefer Daggerfall. Just easier to get into for me.

7: It takes a decent amount of time if you want to really explore, get the top spot in factions, and whatnot. It'll take a really long time if you don't use fast travel. It's technically possible to venture about without fast travel, but the world is randomly generated and not much to look at. Arena requires fast travel, as the wilderness outside cities is endless.

8: Alter the controls before you get into anything. It's easy to change everything so that it plays just like the new games with WASD and mouse look and whatnot.

9: It can, but you need to use DOSbox to get it running properly. I think it's included with the games now, and there are easier installers floating around the 'net that automate the process if you're not certain about fiddling with DOS.

10: Yes, the two games are available completely free in their sections on elderscrolls.com.

Thanks for the answers/suggestions!
But I have no idea what DOSbox is. I absolutely need this to run Arena/Daggerfall? And should I mess with the settings, and if I should, which settings?

And would you recommend DaggerfallXL when it is released?

DOSbox is an emulator for dos-based programs so they can run on modern computers. Like I said, there's at least one installer for Daggerfall floating around out there so you don't have to mess with it or anything. Pretty sure there's one for Arena as well. In-game, I can't remember messing with any settings except for making it control like the other games, so you should be fine there. As for DaggerfallXL, I'd have to mess with it when it came out, but it looks pretty nice.

Thanks! I prefer not searching the vast expanses of the Internet to find this thing.

Now, talking about Daggerfall, what kind of stats should I go with? I'll probably play as a Khajiit, with speciallization in Short Blade and probably Axe. Recommend any skills and stat set-ups?

http://uesp.net/wiki/Arena:Files

http://uesp.net/wiki/Daggerfall:Files

Thanks! I'll use them once I get my new computer. Any suggestions for reducing crashes/corrupt saves?

http://uesp.net/wiki/Daggerfall:Corrupted_Savegames though I never encountered any in either game. Just save often and in multiple slots (ie, don't overwrite one single save over and over again). It wasn't unusual for me to keep over thirty different save files in Skyrim for fear of corruption. Some forum-goers keep 100+ different save files.

Install the latest patch and and the unofficial patches "DFQFIX" and "HACKFALL" and you should be all set (both are found on that page I linked earlier). I'd also download Dark-Elves.zip just because.

Daggerfall is definitely the buggies of all TES games, but in its current state with official and unofficial patches there are few if any actually game-breaking bugs. Just make sure you save a lot and you'll be fine.

Start off with Arena - it's simpler than Daggerfall, and has an easier learning curve. That simplicity allows you to play the game without getting constantly frustrated, and when you're finished with your Arena character and are familiar with the way the game works you can then move on to Daggerfall and appreciate the additional features it adds.