As a cinetist, you have basically 2 choices to do :
- select your element
- if available, select which blast to use : energy or physical
The type of blast (energy/physical) will impact the answers to your questions.
With energy blasts, il will be easier to hit (touch AC) but you will have to bypass Spell Resistance and Energy Resistance.
With physical blasts, you will have to deal with normal AC and DR.
1 : If you use an energy blast, you will hit touch AC so you can go for Cons/Dex. Il you choose a physical blast, you will hit the normal AC and you need all attack bonus, so Dex/Con
2 : Elemental form is useful only to have reach on melee attacks. So it's useless if you don't want to use kinetic blade/whip.
3 : You are right, the cinetist has some "spells" as permanent SLA or all day uses. Many don't need to use burn to use it.
5 : You are right, there isn't many available wild talents at high level. With earth, at 10 level, you will want Spark of Life and Earth Glide. At 12, "Ride the blast" is good (teleportation). If you select a secondary element at 7, you will want to get wild talents of this element. In 3PP, there is some good utilities (plane shift).
6 : I recommand to get a composite blast without half energy damage that could be resisted with energy resistance (like magma blast, resisted by fire resistance). To have versatility, I recommand to get a second element to have more choice on wild talents.
7 : Kinetic blasts count as magic weapons only and bypass only DR/Magic. Rare metal infusion allows you to bypass DR/cold iron (all feys), DR/silver (metamorph) and DR/Adamentium (constructs, buildings, doors...). It's a good infusion to take.
8 : kinetic blade is useful if an enemy with reach is at 5 feet. You can't 5 foot step to avoid an AOO when you range attacks. Kinetic blade can be useful at low levels to go in melee if you don't want malus to shoot in melee. With a whip, you threaten the area and can have AOO. At high levels with iteratives attacks and AOO, melee builds seem to have a higher DPS (but you will need a better AC).
9 : Hurricane whip is a single attack to all ennemies at range. With whip and kinetic form it's a lot of squares threaten.
10 : there is lots of 3PP contents. I highly recommend you "the Ultimate Kineticist Compendium" which is a bible of most 3pp contents(and core content). I don't know for 3pp elements but the addition to core elements are good and not overpowered. You have many (many) archetypes, infusions, wild talents and feats.It should be the official kineticist core rulebook.
11 : in the 3pp kineticist compendium, there is some alternate basic utility wild talents but i don't remember if there is an alternative for all elements (there is one for earth (Glass Canon) and water (Basic cryokinesis)).