Unless you are mechanically inclined and familiar with small engines, do not take the engine apart.
Sealing the magneto case is recommended. Use RTV silicone where the wires enter the protective sheath as well as around the plastic retaining nut where the wires enter the engine case.
RTV is not fuel resistant. Do not use it on or in the intake manifold. Use SealAll or Hylomar instead.
There is no reason to seal the top cap of the carburetor slide or where the throttle cable enters the adjuster in the top cap.
Teflon tape can be used to create an interference fit between the threads of the top cap and the threads of carburetor body which will help prevent it from vibrating loose, although I never have had this problem when I tighten the top cap properly.
Do not under any circumstances what-so-ever
use any sort of sealer or Loctite product on the factory side cover screws. They are made of a very poor quality metal and the heads usually strip out when you try to remove them for the first time. Also if you were to seal or loctite them they can easily snap off inside the case when you remove them creating a real nightmare problem.
The factory hardware should be replaced with quality hardware that will never give you any of the aforementioned problems. SBP sells a very good quality kit at a very good price. Hardware kit HERE
A small drop of Loctite 242 Blue on each bolt can be used with the SBP hardware if you wish.
Some folks hate Loctite and never use it. They just check the hardware regularly and snug up anything that comes loose.
Also read up on the threads for beginners to learn more about these engines and the care and feeding that they require.