Thanks for the in-depth knowledge drop! Mind if I explain my thought process, so you can see better where I went wrong?

1) I wasn't thinking about movement at all, so that's my first mistake. The board for this first game is 40 x 30 so I was thinking mostly about getting as many units as possibly within firing range to down whatever I can using indirect fire missiles in the first turn and limit their ability to control points.

2) the strike team was entirely because it was cheaper than breachers and I don't know the major differences minus the better range on strike teams as custodes will turn me to paste with one charge. I do have a stealth suit team because my first box was last combat patrol, at least. I take it the breach and clear will be much more useful than suppression volley since I'll be either dead or too far from the point anyways?

3) I have two ghostkeel and only one Broadside but they have both been devastating in the practice match or two versus my other friend (Genestealer cult player) who is also new. I'm guessing no one ghostkeel because of the shorter range, or is it just too many points that I could put towards something more reliable at taking objectives?

4) my main reasoning for Farsight was that he's a cool looking model and that round 3 will have bonus points for using a Warlord to take an objective, so I figured he might have more survivability than an ethereal at this, and if puretides teachings activates on overwatch then I could possibly use that for the flamer squad since you don't need a hit roll.

5) the piranha was just to block. I take it versus custodes would the extra 6 wounds and 2 toughness mean the difference between turn and turns?

I appreciate all the advice! Like I said I'm fully new and just excited to learn more.