I'm sure others will respond.
The Mac is 12 years old; Apple considers it obsolete and it is no longer support by Apple in any way. That includes official Apple parts. If you need parts in the future, you'll be limited to places like eBay if you can find them at all.
As old as the Mac is, it will never be able to run the latest secure OS and that includes Safari. That being the case, you can expect certain website to balk at loading. Firefox may be a solution to that.
The thing to consider is how much time, effort and money are you willing to invest into such an old device? Pretty much any amount you do spend will be greater than the Mac's worth.