1) To clear up the TR vs E question, these are absolutely positively unquestionably Ethernet and Ethernet only. The 3 = Ethernet/5 = Token- Ring was for the four digit products, in which the first digit referred to the category of chassis (3000, 5000...), and the second digit referred to the datalink (3 for Ethernet, 5 for Token-Ring). The 28K absolutely did not fit into this numbering scheme.
2) This product came out right around the acquisition of Synoptics by Wellfleet, and IMHO represented one of the best missed opportunities of Bay Networks. The price and port density were vastly better than the Kalpana, and management could be done by a simple telnet menu based interface. This device had no competition. Unbelievable squandered opportunity. I actually think it came out before the merger, since I was one of the first new hires of Bay, and I remember working on it. Maybe it came out just after I joined.
3) This guy will work just fine as a simple switch with spanning tree, using all the defaults. I don't remember any VLAN stuff on it, I certainly do not remember using any. If there is any VLAN stuff, then it probably predates the 802.1q standard, so it could only do it with another 28K.
Switches are so cheap nowadays, maybe you want to buy a new one rather than have it fail on you due to simple age.