OEM Boost Solenoid/Low Boost Concerns

[gboson]

I'm new to the Subaru as well as boosted arena so please bear with my seemingly naive questions. 

Engine: 1998 WRX STI Version V RA 2.0L EJ207 (Completely stock internals)
ECU: 6S
Turbo: Stock VF28 
Exhaust: 3'' Turboback 5zigen exhaust. 

I currently have an aftermarket MBC (Halman) installed running approximately 10 psi of boost (its a daily driven car).

1. Are there any issues running such low boost? Research suggests that these engines ran 17-18psi stock. 
2. Wastegate pressure (if I remember correctly) is circa 7-9psi. I don't quite understand how I can reconnect the OEM Boost Solenoid, I'll appreciate if anyone can supply me with some images of an engine bay and the appropriate connections etc. Effectively then, will adjusting the MBC to run the desired 18psi be equivalent to reconnecting the OEM Boost Solenoid? IMO reconnecting the OEM solenoid seems safer as proper adjustments can be accurately made by the ECU. 

I recently installed an AEM Wideband and A/F ratio at idle was averaged to be 14.7±0.2 and 10.0 at WOT. The WOT A/F ratio seems to be quite rich which prompted my question regarding running LOWER than stock boost pressures and its effect on the ability of the ECU to compensate effectively. 

Prompt replies and any knowledgeable insight will be hugely appreciated. 

Thanks in advance!