mp4 shutters are copal 1, they are self cocking press shutters that have 2 threaded sockets and a top speed of 1/125s
the shutter WILL need a cla, they all do, unless he had his CLA before he sold it to you.
( add that 50-100$ + postage of your CLA isn't local to the price of whatever lens you buy. )
the tominon lenses are not really very good lenses for general photography. i must admit i have a 127 and it is OK ( stopped down )
not a lens i tend to use all the time. the shutter takes a small throw release and if it is a long throw, it slides off the
anvil and gets jammed in the shutter. it was the lens that came with my speed graphic through, so i use it ...
the 135 will work OK ( stopped down ) but if it was me, i would spend the $$ on something else .. the other lenses mentioned in this thread
by whitey, ian, dan, pmk-25 and the others are better lenses, and worth the $$...
if you NEED a shuttered lens, poke around for a symmar convertible, that might be another lens to look into, it is 2 lenses in 1, it cover 4x5 without a second
thought it is paired - the 150 with a 265 -- worth the $$ way more than a polaroid tominon ...
plus all of the other lenses mentioned have re-sale value is more than 35$ ... (people tend to buy these lenses for the shutter, not the lens,
because a g claron screws right into the shutter and they tend to have a large image circle stopped way down .. )

another lens you might look into is one of reinhold's wollaston meniscus lenses, wide open is beautifully dreamy, and with the supplied! waterhouse stops
it is sharp, they also are in your price range and are a barrel lens which is perfect for paper negatives ...
which might be more useful than film to get your feet wet ...
process it in a tray by inspection, and load it in a safelight.

i can't say anything about plastic tanks, i have a yankee, and it has served me well for 30+ years, and it won't transfer your 98.6F to the chemistry ...