Well the "12V DC Coil" should give you a hint as to the rating of the coil eh
Many relays have a similar footprint so you may be able to get a clue as to the pinouts* and check with a multimeter.
You'll be safe with low voltage / Lowish current stuff on the contact/switching side. But, I'm sorry to bang on about it, buying cheap stuff can be a false economy or you can strike lucky.
I'm sure it'll be fine in your low-power app.
*Have a look at websites like Farnell and RS and various others which have a wide range of relays made by proper manufacturers. Those cheapie Chinese (or whatever) will be copies, sorry, I mean designed to a high standard and pin-compatible.
You can buy contact arc suppressors (usu a Res+Cap).. maybe even from Ebay.