[RPG] How do the Sorcerer Bloodline Feats work

Feats are based on character level, not class level

All characters gain a feat at first level, then another every two levels thereafter. This is based on your character level - that is, the sum total of all of your class levels. Your feat breakdown should look like this -

Human Cleric 1 (ECL 1) - 2 feats at first level (2 feats total)

Human Cleric 2 (ECL 2) - No additional feat

Human Cleric 3 (ECL 3) - 1 additional feat (3 feats total)

Human Cleric 3/Fighter 1 (ECL 4) - 1 additional feat (fighter bonus feat, 4 feats total).

Fighter's bonus feat is its class feature and is unrelated to the feats gained through your ECL (Equivalent Character Level).

As far as feats go, Combat Reflexes and Improved Initiative, from your list, are both solid. Power Attack may not be a good choice; your attack bonus will be low for your level and Power Attack may just remove any chance you had at hitting. Channel isn't really the greatest ability to invest in and you might want to consider some metamagic feats instead, as a down-the-road investment.

If you choose the Arcane bloodline then no, there are no bloodline powers that the Halfling favoured class option can apply to. But this doesn't mean that you don't gain any bonuses for sorcerer being your favoured class, you just fall back to the standard options. You can only chose the +1 hit point or skill rank per level.

If you wanted to use the Halfling's favoured class option then you would have to choose a different blood line, one with a power that meets the requirements, such as Celestial (Heavenly Fire power).