Rods and adapters to hold dial indicators?

Have just a bit of experience with milling and started a class at a local community college in the precision machining program to learn some more.

For a lab fee we got some tools: Magnetic bases, center finder, dial caliper, dial indicators, etc. Given a few basics and more or less turned loose doing some simple projects. Seems like most of the other students have a bit of experience too although it's the first class of the program. One remarked that it seemed like they assumed we already knew a little about the material.

Anyway, I am looking at the mag bases and dial indicators and thinking I really need a few more parts to connect the two to be able to really use them all.

Bases:
Mighty Mag indicator base: Has holes for 3/8" and about 5/16" (v hole would work with smaller). Comes with nothing else.
Dasqua switchable magnet base with multi-joint arm with clamp for 3/8" and 0.315" (8mm) rods and dovetail of dial indicator. Comes with a short 0.315" pin in the clamp.
arm threads into base.

Dial indicators:
Mitutoyo TI-115TX with dovetails. Also 3/8" round to dovetail, 0.157" (4mm) round to dovetail, and 0.25 x 0.5" BAR TO DOVETAIL, 3/8" or 0.157 rounds.
H&Hip 7121-0025 0-1" with 0.25" hole in tab on the back. Stem is 3/8".

I see how I can use the first indicator with the second base and put it in whatever position I need. Also see how I could put it in the mill spindle with the 3/8" round adapter although checking concentricity of a round part or hole will be limited to small parts/holes.

I see how to use the second indicator with the second base using the 3/8" stem but have nothing obvious to use the tab hole mounting.

I don't see how to use the Mighty Mag base. I could put the 3/8" pin in the hole but that would give no adjustment to the position.

I seem to be missing some bars or adapters. Where would I use the 0.25 x 0.5" bar mount? What's the purpose of the 0.315" dowel pin? Seems to be just for shipment.