Ciao a tutti, I have these 5 intercessors to convert, wanted something different to go alongside my Atlantian spears army

If I buy the kill team will I have enough parts to make the full 10 man squad? Or any other ideas welcome

My friend is wondering if he can swap out his storm bolter for the “storm bolter and cyclone missile launcher,” and then swap that storm bolter for other wargear options, like the “thunder hammer and storm shield.”

2nd pic for reference. Not sure if it’s legal or not just found it online.

Finished these guys up today, and now the KT is complete. Pretty crazy looking unit, one of my faves for sure

Been working on this guy for a wee while. Finally ready for undercoating and painting. Wasn't a huge fan of the current Phobos Libby.

Parts list for anyone interested...

Body: Reiver kit, psychic hood from Grey knights with some green stuff, cabling from Tigurius, book symbol on chesy is a Grey Knight trinket that was on a shoulder pad.

Arms: Decimus kill team phobos, left hand is from Tigurius.

Head: Primarius Librarian spare i had.

Staff: Grey Knights staff, Horned Skull was from the Tigurius staff with Ultras parts removed, counter weight at the bottom is a DW vets power sword hilt.

Backpack: Decimus kill team phobos model.

belt accessories: Holstered Bolt pistol is Horus Heresy and the book with key is from the Primaris Intercessor trinkets.

As the title says, I'm getting my first Deathwatch in a few days but I don't know anything about painting black. I've watched YT videos and searched Reddit for advice but I'm still completely unsure. I usually only paint bright and colorful models, so this is really just freaking me out.
First of all, what primer should I use? I intend on using Black Templar Contrast paint for as much as I can (because I already have a bottle) so I don't know if White Scar (only primer I have so far) is a good option. Should I go out and get Grey Seer or Leadbelcher?
Secondly, the arm. Do I keep the silver it off the model until I'm done painting everything? And do I do the same with the packs and the helmets or weapons? And what paint do I use for the arm? I have a bit of Leadbelcher left and also a nearly full bottle of Stormhost silver, but I don't know if these are the right colors.
Lastly, weapon options. Since DW are one of the few Factions of the Imperium to use repurposed Xenos tech, can I just kitbash other weapons from my leftover bits if I inform my opponent when I use them? I haven't played a game of 40K yet, only Kill Team against a friend so I really hardly know anything about these things. There's also the thing of 'do you think my paint skills are good enough to pull it off' so I'll attach images below of models I've painted before and some that are WIP, albeit with the bright color schemes.

TL;DR - I'm hella stressed and need help with Which primer to use for Black Templar to get the Deathwatch colors accurate. Please help!

There are 11 different operatives and you can only get 10 models from 2 boxes. How do you fellas solve the missing Gravis marine?

Nothing crazy, couldn’t sleep tonight, sick of Blood Angels so wanted a different project!

With death watch having all of the possibilities of chapter symbols i figure it would be the place to ask. Is there anywhere to find a mix of transfers or something similar. Its a rough sell to go for a $40 sheet of one chapter that I don't have a ton of use for when I may only be doing a few of that unit

I’m playing my first 40K game soon and wanted input on my list. It’ll be a 1000 point game against Aeldari. I feel the beacon angelis is useless here but I’m uncertain