Let´s go step by step.
For the meter, there are several options regarding how much do you want to spend.
Cheap and limited:
Gossen Pilot II (or Sixtino in Europe)
Any Weston (calibrated in ASA-ISO).
Chep because the price shouldn´t get higher than USD 70 for the Weston, which is the most expoensive of them. The others two would run for less than USD 30 as worst, usually you can get anyo one of those for less than USD 15. The metraphot is expensive, because it´s a collector´s item, however is a very good and dependable meter.
Limited because they are based on selenium cells and it means they won´t be of much help for low low light.
Not too chep but almost unlimited:
Gossen Lunasix III (or Luna Pro in the US). One recalibrated for silver oxide or alkaline batteries can be obtained in good condition for USD 65...100 depending on external condition, caser, and if the accesories are available/or included (Labor, Tele, etc. ) the price would be about USD 150.
Ther closeup lens / filters you mention were made By CENEI in Germany, which was a very well known factory of optical accesories of very high qualityduring the ´50s through the ´70s. Perhaps you can place a frosted glass in the focal plane and placing the lens in front of the camera lens, check the minimum focusing distance, with shutter at B.
Regardiing the self timer, the usual is to open the shutter and drop some few drops of Ronsonol (lighter fluid) inside the self timer mechanism to remove the dry grease. I would try to operate it several times until it works without stopping, before trying other means to fix it.
If you are not familiarized with this types of shutters, I wouldn´t recommend you to try to open it and fix it by yourself: the cleaning fluid can drift to other places (shutter blades) and the shutter would end stuck, requiring it to be dismantled and cleaned thoroughly.
Many 35 mm and MF film cameras, some weird cameras... and nothing digital yet!