Advice on frame prep

[Heater63]

Finally, after delays from work (and I am thankful to have too much the past year), I have dissassembly about finished and can start the fun! I am ready to pull suspension and send fame for blasting...a few questions first for you guys. I am building a mild street truck, using L6 292, about 250 hp through a T5 world class tranny..no racing or heavy pulling. I am converting to 4 wheel disc, 5 lug.
1. Any need to weld up crossmembers/frame joints that are riveted??

2. Any need to box or strengthen the frame for street use??

3. Any need to box or plate together the trailing arms?

4. Rear sway bar?

5. Is it best to keep the factory rear emergency brake cabling system ??

6. Frame: Powder coat vs paint ?? is it affordable?

Thanks for all the advice. This board rocks!