That's a slower computer, so one with a slower burning speed might be better. Also, if there aren't any USB ports onboard, be ready for superslow burns.
Any compatible USB or Serial external CD-ROM drive should do good justice. If your ThinkPad supports SCSI interface and has a SCSI connector you can get a SCSI external drive. I would recommend Sony or Creative CD-ROM drive.
There is no such thing as a Pentium 5. That would be a type of processor, except that Intel stopped naming them Pentium before the Pentium 5 came out.
The Pentium brand has been relegated to low-cost / budget processors. Creating a processor called the "Pentium 5" would confuse consumers, who now expect a Pentium to be a cheaper processor, while the name would imply that it was a flagship successor to the Pentium 4.
It would depend on what was broken.
The Thinkpad T42 can be purchased from many places. One place is directly from the manufacturer which would be Lenovo. Another place would be any used computer shop that might carry it.
Celeron doesn't refer to any particular processor series. Celerons were cost-reduced versions of their Pentium equivalents. The Celeron in question could be based on a Pentium 2, Pentium 3, Pentium 4, Pentium D, or Core 2 Duo. In which case the answers would be "Pentium 3, Usually Pentium 3, Celeron, Celeron, and Celeron", respectively.
That would require purchasing a new motherboard, processor, and power supply.
Perhaps more appropriate a question would be "Does PCSX2 support Pentium 4 processors?" The answer is yes. You may not have very stellar performance running it on a Pentium 4, however.
e2200 would be better as it is newer than the Pentium 4 and is dual core while the Pentium 4 is single it has also been proven the e2200 is better than 2 Pentium 4 put together
No. The USB 1.1 found on a Pentium III system is far slower than the memory or IDE bus. You would be better served by upgrading your RAM.
You can have only one stick of ram for an R50 Thinkpad. 2 would be optimal for better performance however one stick will operate fine.
You will at least need a new motherboard. The rest of the hardware in the Pentium II is probably so old that I would buy a new computer instead which has all new hardware.