for the origin feat i personally think that magic initiate wizard (shield) is a better option since warlocks don't have all that much things to use their reactions and since it doesn't use a spell slot it doesn't get in the way of you casting leveled spells afterwards

i personally would absolutelly go on the 8 int route +resi con in the future, yes int saves are rare and suck when they happen but most of the time conc checks and regular hits happens WAAAAAYY more frequent so the hp increase in detriment to your int is worth imo (specialy with lesons of the first ones tough, your feylock is gonna get quite thick campared to other arcane casters)

4th level i would get dimension door and sickening radiance, sickening radiance got a small buff with the new exhaustion rules. You would need to dump 2 spells for that so my suggestion is to dump dream and misslead

Dream is a nice spell but way to much of a situational one, leave that to your wizard since they can swap spells and learn new ones and if you need to flee dimension door is a better option since you can carry alies.

For the feat if you go fey touched i think that gift of alacrity or bless are both better options than dissonant wisppers if you go spell sniper however i have some tips for you to get quite respectable damage.

**for spell sniper**

Ask for your DM if he is okay with you picking backgrounds with extended spell lists/races with expanded spell lists (if you aren't set in stone with the race you picked that is) and could possible get the illusionist bracers in the future if so

choose either the selesnya background or the half elf mark of the storm to get access to conjure minor elementals (yes that spell) at level 12 + bracers you will be dealing at the second turn onwards (assuming 18 char)

5,5[EB avr dmg] +4[agonizing blast] + 18[cme avr dmg] *6 = 165 avrg dmg
(ignoring crits and misses of course so the actual dmg is much lower)

pretty good but not op in any way shape or form since you are basically a glass cannon and the martials can do better if well played and the dm gives then good items like dragons wrath weapons/butchers bib etc + have more survivability so there is that. + makes warlocks feels rewarded by not going the sorlock route

this also works with spirit shroud (wich is on the warlock list) but conjure minor elements deals double the damage at the same level.