O.k., so I'm getting the pc version of oblivion tomorrow. I've already downloaded about 30 mods to my pc and i was wondering if that was alright that i did that before i installed the game. I was also wondering how much of a limit is there on mods, and Are there any performance issues with the unique landscapes mods, I downloaded them all and most of the patches off of tesnexus.com, and does anyone have links to the official patch(To lazy to search around myself), and also does it cost anything?

Yeh, you can have as many mods as you want.
Do you have the mod manager? They're really easy to set up with that.

Ermm with the patches, I dont really use any, but I'm pretty sue they're free, why would you have to pay for something they've fixed on the game you've already bought? lol. Should be alright.

Hope that helped/made sense.

thank you, i guess i should go get that mod manager too.

limit is 255, well 254 since there's 1 spot for the actual Oblivion.esm of course.

conflicts and issues are more down to individual experiences. Such as you could experience one problem whereas I wouldn't get that issue but suffer from another. However as far as I know, no issues with the UL mods, except they can be strain (especially qith QTP III on top) on the lesser powerful PC's

As to downloading them before, nope that is fine as long as you install them after installing the game and patching it up.

Patches are free and can be downloaded from the elder scrolls website or you can use the easy method and just buy GOTY which contains Shivering Isles and the 1.2 patch. It would also be wise to download the unofficial patches made by the modding community that iron out the bugs and glitches that the community themselves have suffered with, meaning if more than 10 people or so suffer with the same issue then they will fix it.