Mamyiya made really good glass, if the meter is active you will got air zinc batteries, hearing aid batteries work for me. It has both spot and average metering and works with single pin M42 lenes. In case you have not looked here in the manual.
I have one of those! It was my uncle's and the light meter isn't working. I tracked down *the* guy who does Mamiya repair, primarily medium format. His opinion was that, unlike the medium-format Mamiyas, the 35mm cameras really weren't designed for repairability, and said the meter repair probably wasn't worth it. "I'd do if it you put a gun to my head," was his exact phrase. (And he wasn't being jerky -- he was a super nice guy and talked to me extensively about the camera.)
I was a bit bummed -- but I am keeping half an eye out for an example with a working meter.
The 1000 DTL takes SIlver Oxide batteries. Not mercury, so no issue there. They were very solid well built cameras using the M42 screw mount, so there's a gazillion lenses that will work. One of the few M42 camera that works with current batteries (see page 6 of the instruction manual that Paul provides a link to).
It was one of the first SLRs I used as a kid in the 60s, belonged to my dad. I still have one now, I quite like them. I really like the average and spot meter function.
Be careful if you are tempted to put the Mamiya SX lenses on a different screw mount body. The open aperture metering pin can drop into one of the M42 mount screw points and make the lens difficult/impossible to remove without a total strip down. I believe some Pentax M42 bodies were prone to having Mamiya SX lenses jammed on them.
Almost all cloth focal plane shutter cameras from that era will need to be cleaned for proper use.
For example, I got this Rolleiflex SL35M from 1972, pretty much new in box in 2005. I finally got around to making a shutter tester a few months ago and this is how the shutter measured prior to cleaning: