I'm new to nitro and I'm looking for my first engine. It will be going in an NT1. Being new I'm sure my priority should be something easy to tune first. After searching the forums and getting recommendations I'm leaning towards the OS .12 TZ. ItI think the version I would need is the 3 port with the slide carb. Is this correct?

Should I consider a "tuned" version of the TZ?
Should I consider any other engines?

I had my eye on the Orion Wasp but I don't know much about it. Would that be a decent alternative?

A few other general engine questions

Do most on road engines have slide carbs?
What specifically denotes an on road engine?
What/where are the 3 ports?
What makes an engine legal/illegal other than displacement?

Sorry for all the questions. Thanks for taking the time.