.1. i use my b600 over any other enlarger sitting around or to which i have access. i have a nice lens on it, so in terms of quality, it out performs any other. i don't need the frills of a pulley system to raise and lower the head...that's why i have fingers.
.2. the tray about which you speak is indeed a filter tray. it sits just below the condensers. do you have a manual for the b600? if not, let me know...i have a digital manual i'll be happy to send to you.
.3. as mentioned above, kodak did make a paper for printing b/w from color negs. you
can print them on traditional b/w paper, but the process of finding the right paper, neg, and filter combination is very tasking. the prints will come out very muddy.
.4. sure; just run a transparency through a printer. you will have to edit the contrast range of the image, though, as the density range of transparencies doesn't equate to a negative. you'll more than likely want to do this (as mentioned) as a contact print i.e. - make the transparency the size of the print that you desire.
metal trays - a very big no no. stick to plastic derivatives.
timer - can one be made? sure, with the correct diagram and construction using double pole double throw switchs and relays, but it's hardly worth the hassle and expense when you can get one for cow dung barter on
ebay.
@Rolleistef - what changes is, in short, focus across the plane. disregard the numbers. open your aperture all the way, then close it down 2 stops. that is the optimal aperture opening for your lens. full open for focus, stop down twice for print. if you need longer exposure times, throw a neutral density filter in there...stopping down too far will cause edge blur or uneven exposure.
*edit - forgot one.
Can you reuse chemistry? what JamesD has stated holds true in general, although the specific chemicals that you use will have an impact on your reality. if you don't yet have chemicals and are looking for an inexpensive way to approach the issue, just ask. if you have chemicals, list them here and we can attach some guidelines for you.