There is a nice application note: PSoC5LP hardware design considerations: http://www.cypress.com/?docID=49353
It should probably answer your questions. Make sure you also read the PSoC5LP Architecture TRM (technical reference manual) and the family data sheet for your device - they answer most of th questions you have.
In short form: yes, powering everything by 5V is OK. If youcare about analog performance, separate analog and digital ground planes (and look at AN57821: http://www.cypress.com/?rid=39677 ). decouple the analog and digital voltage rails with ferrite beads. And make sure each supply pin pair has its own decoupling capü.
I'm not sure how good the LM340 is for analog applications, maybe you can use a separate regulator for the analog voltage (one with low noise floor).
Looking at the schematic I cannot see any glaring mistakes so far.