If the filter is between the supply tank and the vacuum tank that is normal, it is a vacuum system so causing air and volatile fuel components to off gas when they get to the air space in the filter. You don.t need a filter between the vac tank and the carb.
That would depend on the design of the pump. I have used an Autopulse model 600 on my Series14 since the 1960s without a bit of trouble. It is a simple pushrod acting on a bellows and is adjustable for 1 or 2 psi. Don't know which it is set for but it always supplied enough. These pumps were used on Porsche racing cars way back when. They and overhaul kits can available on Ebay.
Time for another Jerry Lettieri auction at http://www.automobiliaauctions.com. Lots #44, 94, 141, 142, and 143 are exclusively Franklin. Lots 218, 228, 234, 342, 383, 390, and 423 have one Franklin piece in a mixed lot. Fox lit in lots 279 and 291.
My 11B had a Dole primer setup, a pump like a tire air hand pump in operation which pumped gas to three fittings on the intake manifold. Have ask Bob Amon where it connects to the fuel supply system on Bertha. It was mounted behind the dashboard with a good sized chrome/nickle knob for your pull-push operating pleasure. Nothing like having gas leaking on the driver's left leg. Tried it once, didn't like it.
Ed Granville lived in Vernon CT, where I live and go by his home frequently as it is about a mile from mine. Decades ago I bought something at a tag sale there not knowing at the time who was holding it and of course now don't remember what it was. He is listed in the '73 Roster and his car, an 11-B coupe, was yellow with black roof and is now in Oregon.