yea wd 40 will clean the dirt and grease off of them if u use wd make sure u re grease them afterwards.
you can buy abec 9 bearings on ebay for like 15 bucks shipped for a new set.
I don’t know what condition your wheels are in, but you might want to consider replacing them at the same time.
i have never used anything on mine, i just replace them if i think they aren’t spinning the way they should lol
i used this lube i got at dicks seemed to work great on my swiss’s. i think its something like bsb lube its in a small bottle for about 5 bucks
get new wheels… whenever i get new rollar blades… i go so fast, i dont know how to stop, unless i fall in the grass or hit a wall.