Honda Civic Forum - new to honda and need help

I hope i got this in the correct area of the forum. I apologize if its in the wrong area.

I'm new to Honda never owned on. (wife's Acura knock on wood never gave me a problem so I don't work on it)

A co worker moved and gifted me his 2002 Civic, with a quick rundown on the car. I'm not sure how to start this porject.

To start car runs and drives with issues.
Motor has been swapped and same with transmission. I need to figure out what motor is in the car and transmission vs what came in the car. I'm not sure if he did a V tech swap or if they came this way. once I figure this out I have to get the transmission sorted. When I drove the car the clutch slipped now it doesn't after getting to the house. I have a feeling it needs to be changed and the massive oil leak needs to be fixed from the valve cover gasket to keep the new one from being contaminated. So that being said how do I check the engine and transmission numbers to make sure they are really compatible? I've read in other websites that some will work but spacing and clutch engagements are never correct and it will just waste clutches over and over again. If they are compatible and I can get the correct parts for a clutch job. It pops out of 5th gear at highway speeds (over 55) this is something I need to track down and figure out as well. it stays in gear if you hold the shift lever and apply slight pressure towards the 5th gear shift pattern.

what tags do I get numbers off and compare to see if everything is compatible? how do I check the numbers to a list of known swaps if he indeed did do something out of the normal?

Thanks for the forum and this is just a start of things to come. I really like the car and am excited to own one. Never had a Honda nor a two door before so this is fun and I am looking forward to owning and driving the car.