They are very low risk savings products.
I bonds are up there is because the owner of the bonds charge interest on those bonds that is where Ibonds came from and they have to make money as well and as like everything Interest is always high to begin with
To change the registration on a I treasury bond you need to have it reissued. Check out http://www.treasurydirect.gov/indiv/research/indepth/ibonds/res_ibonds_ireplace.htm for more detail on reissuing a bond.
I Bonds can be purchased in any amount over $25, but there is a purchase limit of $10,000 per social security number. They offer a fixed rate of return and interest compounds semiannually for 30 years, according to TreasuryDirect. They can be redeemed after one year. You can order bonds at face value through TreasuryDirect.gov.