Nice machine is you are planning on tapping channels by hand.

Your first drill chuck is for you center drill bit, the second for your pilot drill bit, and the the taper with collects if for your tapes.

As for the dial you asked about, it your depth of channel.  Hence you zero it out against the work piece, and give you control for depths of bind channels for bind channel drilling and tapping.

As for drill speeds, easy enough to figure out,and start with the RPM of the motor.   When both pulley are the same size, then the spindle speed will be the same as the motor. as the pulley on the motor decreases, and the pulley on the spindle increases with the belt on it, then increases the speed on the spindle isntead.  So basic tape measure of the pulley sizes against each other, will tell you the reduction or increase speed percentages of the spindle verses the constant motor speed.


As for the press, would start with pulling the lower quad head drive, to check it bearings/spindles, and make sure it not littered with chucks of sheared gears.  The chucks pull apart like standard chucks, so a good time to clean them up and lube then as well.  The quad tapper   is straight forward to pull apart as well and again, since it runs a collect system to remove as much run out as possible with the system, may need to have it's bearings replaced too.
How the tapper works,


As for the main spindle, can't remember if it bearing or shim, but easy enough to pull apart to check and clean up as well.

Lastly, the pulleys where not know to be balanced, but chances are is not the source of your vibration.  So when you have it apart to clean up, try to balance the pulley, then the rest of the vibration will be worn bearings isntead.

Ditto on the base, and would just mount it to a large 1" steel plate that is mounted to the bench.  This will give the machine enough rigidity, plus have a base plate large enough to mount a X/Y vise to as well.

As for a X/Y vice, hate to break the bad news, but unless you want to drop some serous coin, going to be looking at rubbish isntead.  
Most cheaper units have so much lash to start with, that unless you have a DRO on it, your never going to be able to find the same channel on a repeat return to.  Hence the reason for the press in the first place, since once you spot in the work piece, then its worked through all the processes to  a finished taped channel before the work piece is moved again.

An X/Y table with T slots for clamping will work, but may still that you may still need a vise to clamp to the table as well.


But again, the glitch with the X/Y cheap tables, is they have so much lash in them, with a DRO that is reading the actual table movement, the crank dials almost become worthless for a return to repeat via the back lash.

Also, keep in mind that the X/Y table is going to eat up usable spindle head travel, so depending on the height of the X/Y table (and even vise mounted to it), may need to extend the column support on the machine. On the positive note, the column suport is already rusted to hell, so depending if you can not get it cleaned up enough for every a coat of paint, it pretty cheap to just get a longer pipe column isntead.

As for your  depth indicator, may luck out and just needs adjusting since in not seeing a disengagement for it, but don't freak out if you find teeth missing from the engagement gear instead.  Hence on some machines, they had a disengagement for the indicator, since you could not set the pilot drill tip and ream tip to the same depths to the work piece, and this allowed for a quick re-zero as you make the tool holder index change.    With your smaller machine, should be a problem, since you can set the depth of the pilot drill in the drilling chuck, then leave the reamer semi-tight in the collect system and slip the reamer up in the collect to set both to the same indicator zero's.


Lastly, as you can tell, the machine did get a repaint, but to what extent the machine was pulled down to service during the re-color, is very suspect at this point.  With the machine fully pulled down during the recolor to do a full servicing on at the same time, it would have been too easy to just bead blast the parts to remove the old paint, and then prime and repaint the machine correctly instead (not new paint layered over old paint chipping off instead).

So on that note, as you pulling the machine down for a complete servicing, don't be surprised to find parts that need to be replaced.  Even with the age of the machine, it not hard to cross reference to find replacement parts, and even the parts on the cheap that someone had laying around in a box that they never got around to using.

To bottom line it, it's fun to pull down old machine to bring them back to new for occasional use, but in the long run if you plan on using the machine for actual production work isntead, not the best of ideas.  Hence with the New CNC machines with tool changers, what you spent on such up front, you make back very quickly in regards to production man hours instead.