Today we have most of the answers to these question, directly from the CEO, Elon Musk.
(1) 30 Tesla Model 3 cars will be ceremoniously handed over to first 30 customers on July 28th. 100 cars should be produced/delivered in August, >1500 in September ... >20.000 in December. All reservation holders should receive their cars in 2H2018-1H2019.
(2) The range of the first Model 3 cars will be around 300 miles, as a test vehicle was photographed at a supercharger and showed 95 mile range, when charged to 36%. So this is for the bigger/expensive battery pack (70-75kWh), while the smaller/cheaper battery pack (55-60kWh) will offer about 250 miles of range at the 35.000 USD price point.
(3) The Tesla Model 3 has one 15" center touchscreen, where the big majority of controls are accessed.
(4) The interior will be black, minimalist, improvements to cup holders, phone holders and other storage spaces.
(5) Model 3 frunk + trunk storage space is roughly half of the Model S, 14 vs. 30 cubic feet.
(6) Level 5 autonomy capable hardware will be preinstalled in all Tesla Model 3s, while autopilot features will cost extra, when they'll be available.
(7) Rear wheel drive cars will have an acceleration comparable to the first generation Tesla Model S. Faster and dual motor AWD models will come later, probably in 1Q2018.
(8) Durability of ALL NEW TESLA POWERTRAINS are being improved to 1 million miles
These are the most important details in my opinion. Tesla is finally releasing an affordable and extremely durable mass market car. Model 3 will be perfect for travel, city driving, taxi services, company cars and even for some light towing/delivery jobs.