A Question of Temperature ??????

Firstly I have learnt so much from reading a lot of your posts and thank you all for the extensive lessons. A bit about my grow history I have been growing for approx 30 years outside and have recently last 3 years moved inside. I live in a part of Australia where daytime temps can reach 42C which is approx 108 F. To prep the soil we use water crystals and lots of mulch, and cover the plot with some type of hay to slow the eveaporation. Now my question is, What is the difference in the effects of temperature inside and outside??. I notice the real big setups have air cons to keep the temp at 75-80F, i know about the photosynthesis rate slows at extreme temps. What I want to find out is people's experiences growing indoors when the temps get above 95F. Also I would like to find out about what humidity and what the babies prefer. I am fortunate in that the setup is quite large and I dont need to have a closet set up, I am using a room that is 18" x 10" with a roof height of 10". at the moment I have one 1000W HPS and want to go up to four. But first thing is an answer about the difference in the temp from the sun and HPS lights.

Thanks.

Andy