I've not had problems with engine bolts falling out, therefore I don't believe loctite is necessary, and is just asking for trouble and aggravation later.
For sure don't over tighten and deform sheet metal parts, then they do leak.
Follow Tim's advice.
Or I use gasket cement (contact adhesive) to similar effect on sheet metal covers/pans, one side only. Oil or grease on opposite side of valve cover so it's reusable. Permatex #2 on the other (or both sides) of gaskets I don't expect to save at disassembly.
