I was wondering if it has the Ikea stuff pack.

Yes, all EPs and SPs, patched.

It does, including the mini Holiday SPs.

Yes also is the most compatible with Windows 10

How so?

I think there was small update for UC in 2019 or 2018 which was supposed to do that.

UC does work quite well with Windows 10; there was some updates; one in particular made it easier for Wndows 10 to read the longer names of files in your cc.
I remember at the time looking at the game after the update and could not notice any difference - until I wanted to buy a new bed, and my buy catalog had some beds in that never showed before.
Securom has also been removed from the UC.

I started using the UC when it came out on Win 7 (I happened to break my BG disk shortly before that) and moved it over to Win 10 when Win 10 came out. No regrets

You will probably have to change the graphic card, though - but I don't think that is limited to Windows 10.

With the latest patch EA got rid of the (finally) pesky copy protection which was delivered (not for everybody, though) with the copy of the game and did not work well, or not at all with the Win10. This patch has made Win10 victims' life much easier obviously.
However they also infected the executable with mandatory Origin service. Just one trojan replaced by another. But if you're happy W10 user, you probably do not care anyway.

"there is always good time to screw our customers".

//EDIT: my wonderful grammar

Although some of the holiday outfits are missing, but there is a fix.

Is there anywhere you can get that now? I've been using my old cd-roms and no cd cracks for years and they worked until I got my current pc. They refuse to work on this one and it's driving me crazy. I was also wondering if I'll be able to use the Sims 2 folder from my documents with the UC. How do I keep my neighborhoods, sims, etc?

Fokusia, not sure about how to get the UC, but for the files you should be able to swap the contents in the The Sims 2 folder in Documents from your old game to the same folder in the UC game (delete/remove files after installing the game, then copy over yours - don't let them overwrite!). Basically how you'd restore a backup.

I did have some issues with this, but I think it's just a matter of me having a somewhat borked neighborhood that worked fine on one computer but refuses to work on all others (lots crash when I try to visit them). Could even be CC-related (I did some Downloads folder sorting before the UC install). In theory it should work fine without any issues.

You cannot legally get UC anymore. EA doesn't sell it, and they stopped giving it away for free about a year ago.