Yes, you can use Carb/Choke & Parts Cleaner to clean any metal parts. There won’t be any compatibility problems. To be safe, it should be kept away from plastic or painted surfaces. Most will be OK, but not necessarily all of them.
Use Gumout 2-Cycle Oil at the treat rate recommended by the engine manufacturer. Add it to gasoline and mix until uniform before starting the engine. Usually, adding the oil to the tank before pumping in the gasoline will mix it adequately.
No. Gumout DOT 3 Break Fluid can only be used in vehicles that call for DOT 3 fluid (the most common type). This is generally specified in the owner’s manual and on a sticker or label under the hood for the particular vehicle. The proper fluid must be used as specified.