If you're wanting to keep your "boys" full, then hcg 350iu-500iu e5d throughout your cycle will do the job. But if it is a more harsh cycle in regards to doses, stacks and duration, then even the periodic e5d hcg won't solve the problem completely. I've run my cycles with and without hcg and it can have a positive affect on how your body will react once you go off cycle. Is it 100% necessary? No, but it is a precaution that will not hurt anything and does have positive attributes.
As far as sub-Q injections, this is fine but it is more of a preference. I have never noticed any difference injecting it sub-Q or IM, so I'll typically just put it in the same syringe as the AAS I'm pinning that day.