#1
Can I replace these tubes with any other tubes or do they have to be Mesa/Boogie ones. (sorry if this sounds noobish)
I'd either put the ones from an F-50 or a higher end Mesa/Boogie set of tubes in or some that give it a sound that is like the Orange amps (love that sound )

Would tubes from an orange amp reck the Mesa sound or give a good blend.

The F30 has only 2 tubes in case that makes a difference

cheers,
#2
The tone of an amp is reliant on a lot more than the tubes used to amplify it. The power tubes, the 2 tubes you are referring to, have to be the same variant of tube at least, which should be a 9pin EL84 in the F-30. F-50s used larger 8 pin 6L6s which are a completely different tube that wouldn't fit in the sockets on the F-30.

If you had octal tubes in your output stage, you would've had more options, given you have the capability to bias the tubes correctly, but you are pretty much stuck with EL84s if you want a modern production 9 pin pentode. I know a lot of people usually like JJs when it comes to modern production power tubes.