I can confirm that my B525s-65a (as supplied by Eternal Comms) definitely has the Bridge Mode option (under the Settings > Security menu if I recall correctly - but it's definitely there, haven't tested it yet).
As for the RJ11, I too am interested in this. I haven't tried yet - waiting for my Three AYCE SIM to arrive next week before I can have a real play around - but I'm searching the web for info on this.
I did find this answered question on Amazon, which is a bit confusing because Huawei say one thing ("no" - indicating in my mind they intend it for VOIP), and a customer (the top answer of 2 on that page) says "yes" (quote: "This seems to be a WRONG ANSWER from the manufacturer") - here's the link anyway: Amazon Q&A on Huawei B525 RJ11.
I will experiment further with the RJ11 connection & a phone once my Three SIM is installed, will report back next week.