There’s little to no benefit from leveling up dirty pole and ice pike past level 1, so not sure why Chiro-Hisuke is suggesting this is fine. No, leveling up pike doesn’t increase your CC.
I know it seems like you want to put more points into summon skill points to make it feel more like a summoning build, but to tell you the truth the scaling from summon skill levels is negligible since the majority of the scaling comes from SPR stat (and attributes for necros). You will hardly notice a difference in damage between salamion level 2 and salamion level 10. If you want, you can take points off of summon familiar to put into salamion, but I recommend taking summon servant either way. Downside is summon familiar is better bossing than your salamion since it isn’t as affected by boss CC, doesn’t rely on bad AI, and is affected by chapparition buff (which is a huge deal once you get your gears).
Endgame content in this game is largely party-oriented, so it’s not a waste to increase your party’s effectiveness. In all of the endgame contents, salamion is actually still quite horrible since his attacks are all single target (necro summons at least have aoe) and he gets knocked back. I can assure you 5 extra points into salamion is not as effective as 5 points into servant in endgame (even after salamion gets stronger with the summon buff).
The Servant’s AoE attack ratio buff also benefits YOU because Flesh Cannon and Snow Rolling both have limits to how many enemies they can affect, and this buff will increase it by a lot. The 50 magic defense/ dark attk is also beneficial to you. Flesh Cannon is also one of your main sources of applying Decay debuff to make your Temple Shooter stronger, so being able to hit more enemies is a huge benefit. Shoggoth is often sloppy with applying decay (though he will be your main source), and dirty pole has a long cd and small aoe.
The cat moves around with you, and the buffs last for 5 minutes (that’s a long time). You don’t have to channel the skill or anything, so it’s not a waste of time. There are plenty of situations where you can use the skill to get all 5 buffs and lose nothing from it.
Main consensus is SPR is a multiplier of your summon’s damage.
Summons have a base damage that is based mostly on your weapon’s magic attack stats (transcendence counts, gems unknown)
It is unconfirmed what leveling up the skills do for summon since grimoire is broken (displays stats incorrectly). It seems like leveling up the summon skills adds that % as additional damage and defense to your summon, based on your magic attack (so INT affects it by a small amount). Either way, the gearing up should look like this:
Full SPR, get the weapon with highest m.atk you’re willing to farm for (Regard Horn Staff is the best, but you can settle for a 1 practonium weapon too), and then transcend it. Best armor set is solmiki, but before you get that you can choose to get War Mage Armor with Suurit plate pants (give SPR), or Vienti oksinis full armor set (expensive and rare though, it is a good endgame set).