100 mgs per week is a normal starting dose. Where you land with your serum & free T level remains to be seen. Thing is to start low to avoid side effects and then titrate up if needed. Remember it's not a race, it's a journey here. Slow and steady wins.
HCG can be initiated at the same time as your T and in the same syringe if you like. SQ injections are a proven effective method for TRT. Let personal choice prevail whether you go IM or SQ, or both:
Subcutaneous administration of testosterone. A p... [Saudi Med J. 2006] - PubMed - NCBI
The main point of twice weekly injections is more stable serum levels of T as well as better estrogen control. Think less injected at one time = less spike in E2 levels. Your goal should be to avoid AI usage if at all possible.