For 150 to 175 you can use 1 5/8 x.120 roll bar tubing I would use DOM,,, and if you ever think you may want to go faster you may want to use 1 3/4 x .120 DOM,,, and yes swing out bars are OK,,,, Competition Engineering/Moroso makes a swing out kit as does Art Morrison and several other companies.
As to a bench seat,,, I am not sure,,, but I am not going to use a bench seat over 135... so ask Joe Timney from Delaware Chassis Works,,, he can help with the seat question.
No safety film needed for your speeds.. also factory glass is safety glass (laminated) so it is OK.
Keep us posted,,
Charles