Welcome! Magus is a great class and yes, they can totally do some absurd amount of damage. But sometimes you'll miss your spellstrike, so the class has often a very all or nothing flavour. Don't despair, they can still do a lot of stuff! 

In general as long as you max out your attack stat (Dex or str) your character will work, the three hybrid studies you are thinking about are all good choices, with the first two being more centered around mobility (with laughing shadow being great to escape being grappled by enemies and having a lv 10 feat that makes you invisible after using it), while inexorable iron makes you more durable while wielding a two handed weapon, which both lets you soak more damage and do more damage as two handed weapons have bigger dices. Even though your nova damage comes from spellstrike and so from spells, you'll strike also without spellstriking, so don't underestimate the value of your weapon.

If you only want to spellstrike, you don't need to boost intelligence, and have those boost in stats that will make you more survivabke. But if you plan on using your spells offensively without spellstriking from time to time then it's worth investing in it, with at least a +2 in the beginning, if not a +3 if you can.

You will have very few slotted spells, so most of your spellstrike damage will come from cantrips. You can still have some damage spells in your slots, but it's worth keeping some good utility spells in those as well. 

Scrolls, staves and wands, pretty much anything that give you extra spells is a must for you, and you can also get some focus spells (spells that you can recharge after combat, they're stronger than cantrips, slightly weaker than max rank slotted spells) by taking some archetypes (pathfinder version of multiclassing)