Hi Westport,
If you have the space go 8' x 4' 6" the extra 6" will make all the difference. Code 75 is a good choice if you are planning to run all new stock but old rolling stock will have problems running on code 75.
Flex track is the best choice as it looks much more realistic. Electrofrog points are also a good choice.
To switch points using DCC you need a decoder which will only do 4 points per decoder or you could use an analogue control panel with switches.
It is possible to wire up a control panel with LED's to show route indication, the seep point motors have aux switches built in which will also switch polarity as well.
I am doing a special offer for this month for free shipping on baseboards, an 8' x 4' is €290 and I can make it 8' x 4' 6" for no extra cost.
I also do a servo point motor control system that is very competitive it is available with a DCC module that can control up to 192 points! I also offer as part of the system switches, LED's power supplies. Typically works out about €16 per point all in, cheaper than buying the seep and DCC module(s) switches and a power supply and LED's
I also build control panels.
Please feel free to contact me to discuss further.