I see a way to a solution for problem #1 - if there is any other working Mac of the 5x00 or 6x00 series (including the 630s !) around, check the 225 motherboard (if the AC/DC down is dead, the fan won't run) in that computer. They are very easy to unmount. Just pulling (but with care). Does it show a 'ready' green LED then, do the drives spin ? Check the voltage of the battery, it should be 3.6 V (3.5 will do) with something attached (a battery not connected to anything will lie).
The AIO Mac wasn't sold in Europe - no idea about that one.
To be continued :-)
The problems with the Performas and the SE may be the result of weak batteries, too. Try to start from external SCSI drives of any kind, if the original installer software or an equivalent is available (eBay ?): it's always good to have them in stock. System 7 had individual enablers for the different models, that makes it confusing, but any version of it is available for free at Apple's site.
And, btw, it's a pleasure noticing younger people are interested in these older machines and computer history - we'll get them working !
A thing you can try with the Performas is a start with the key combination opt.-cmd.-R-P pressed - this is for to reset the PRAM. And you do not need to have a hard drive with these computers, a Syquest or a Zip drive (as iomega supplies) with the system on it will do; the key combination for a start from an external disk the is opt.-cmd.-shift-DEL.
If you can load the System 7.1 disks from Apple (for free !), the floppy titeled 'Disk Utilities 1' contains a minimal system to start up with. And some usurers supply you with ready made disks, too.
This offer is somewhere on the RMC, but I don't remember where it is.
I think it does, and on earlier models, no matter if 6.0.x or a version of 7 is installed. Works on many PowerMacs as well.
To start from an internal CD-ROM drive the "c" is used (without the command-key !).
Another important key combination to start up with is opt.-cmd. to rebuild the desktop. A Mac does it by itself if necessary, but one should do it every once in a while.
Simply follow the menue tasks, well, and I do not know the titles. In the German version of Tiger which I use, 'Grab' is called (fasten your seat belts): 'Bildschirmphoto' and the German word 'Grab' (pronounced with a long 'a' vowel as in the - British English: 'graph') has the meaning of 'tomb' or 'grave' in English.
So we've learned a lot this morning and are allowed to stay home.
At the times of System 7 throughout to 9 there was a key-combination, cmd.-shift-3 to capture a screen photo in 72dpi and in SimpleText-PICT format.
That was (and is, on a machine running one of those systems) much easier.