New (to me) enlarger, have some questions

I just picked up two Durst Laborator 1000 enlargers. Both came with a Pavelle 401 color head, timers, fan, and a bunch of Nikor and Schneider lenses and 6 carriers plus spare parts.

They are both set up as wall mount, but luckily came with the bracket to mount on a table, but no table so I have to make one for it.

So here are my questions.
What is a good size base board to make for this enlarger? I was thinking 24" x 24"
Any issues with using the 6x7 carries with 6x7 if I mask it at the head?
It came with two 80mm lenses, a Nippon-Kogaku EL-NIKOR 80/5.6 and a Schneider Componon 80/5.6, Which lens do you think would be better for B/W?
I hear you can adjust the mixing at the head to mimic contrast filters, is this correct?

I think you have two six-element lenses, use the lens with less haze.

Maximum magnification with a 80mm lens is 11.5, therefore 6cm x 11.5 = 69cm. So I'd make the baseboard around 80cm wide (31"). The baseboard needs to be very thick, otherwise the enlarger head will wobble. My Omega 4x5 enlargers have 1.5" thick baseboards.

Masking reduces flare and improves printing contrast, however, you may not need any masking to use a 6x7 holder with 6x6 film.

The one I have has an original base board, 25"deep, 22" wide, 1.5" thick. Regarding color head, your correct, can use for B&W variable contrast papers. I don't understand your carrier question. Good Luck.