Short answer, understanding in point 2 is incorrect, point 3 is correct.
When you say return is around 7% that is essentially rate of interest paid,
Taxation on interest payout is at slab rate so in a way bond taxation is same as FD.
There is a chance that if you sell bonds before maturity, then you might make capital gains (or loss), only this capital gain is taxed at 10%. But generally this is very small portion. Most of your bond income comes from interest paid out, which is taxed at slab
All Gsecs pay half yearly interest. Shubh maintains a list of govt. bonds and their interest payout date. This is good reference to find out interest payout dates. Or you can simply search with ISIN
For GSec you will get interest payout every 6 months (Which is taxable at your slab rate). at maturity you will be paid face value of bond (this might be different then what you invested to buy it)
Also if you hold till maturity, there will be no capital gains (or loss).
Hope this helps.