Yes, being a pure bomber with only two weapon slots is viable and fun. I do it quite frequently. You do not need any sword or gun sidearm, especially because you have a teammate who can handle the grunt work of breaking blocks, hitting switches, etc.

* If you want to play a damage role, then get two damage-oriented bombs. For beginners such as yourself, the most important ones are Dark Briar Barrage and Dark Retribution. They are easy to use, put out a large amount of damage, and don't disrupt your teammates.

* If you want to play a support role, then get two support-oriented bombs. The most important ones are haze-style and vortex-style. But your teammate's weapons don't make good use of vortices. So go for haze, such as Voltaic Tempest.

* If you want a balanced approach, then get one damage-oriented bomb and one support-oriented bomb.

By the way, bombing requires detailed knowledge of monster AI. So it is sometimes challenging for beginners. If that describes you, then maybe retreat to swords and guns until you master the AI.

Ditch the Drake Scale Shield plan. For defense get Grey Owlite or Dread Skelly, depending on the status threats that worry you most. For offense, especially once you branch out from bombs, get Swiftstrike Buckler or Barbarous Thorn Shield. (In my opinion, your friend should also ditch the Cutter/Antigua plan. In fact, I agree with almost everything Midnight-Dj said above.)

To learn more about bombing, check out the Bombing Guide on the wiki.

You don't have to destroy blocks. Your teammate will do that using his fast weapons.

If you want to know more about swords, then consult my detailed sword guide. But I stress that two bombs is quite viable.

AoA is a great bomb, but it's the least support-y, most damage-y of the haze bombs. So your plan is pretty damage-oriented. But that's fine. Have fun.

Now the thing that must be said about your friends loadout is that what alchemy path is he going to follow? There are 3 different 5* versions of the Antigua: argent peacemaker (elemental) sentenza (shadow) and gilded griffin (piercing). Depending on what he choses, the next weapon should be a different damage type than the other. This also can be tricky as only having two guns can leave out certain other strong guns and make the killing of monsters more of a pain. What I would recommend for your friend is to get 3 guns instead of 2, allowing for a little more flexibility against monsters. Let's say your friend chooses the sentenza (shadow damage), he should then pick an elemental gun. I recommend the Arcana, as it is quite powerful and does not require much accuracy like the alchemers do. I would also recommend getting the blitz needle (piercing damage) as my experience with it is that it is very effective against almost all monsters weak to piercing, such as fiends and gorgos. It also is the staple weapon that almost all players bring to the final game boss Vanaduke. Now the loadouts can change quite a bit if he chooses different weapons, but the one thing he will have to work on the most as a gunner is, like bopp said about bombing, learning the monsters patterns of attack and movement so that he can adjust accordingly and make his gunning experience easier. The one Antigua line I would not recommend him getting is the gilded griffin (alchemy line is antigua , raptor, gilded griffin) as the damage output against the monsters it is strong against and the beast families attack patterns make it quite difficult to use even for me as it requires a lot of prediction capabilities to make it work. The sentenza on the other hand is quite good against its families of slimes and gremlins (though the gremlins do have a tendency to dodge when being shot at, which is not that much of a problem). Now if your friend picks the argent peacemaker (elemental damage) he should go perhaps for the grim repeater, or if he likes the idea of the blasters, then he can go for the phantamos, the shadow damage version of the arcana, though if he is not that accurate then dealing with gremlins might pose a problem. And of course piercing should be the blitz needle.

Just remember that this is all my own personal opinion from my experience, and in the end its your friend's choice of what he gets in the end.

Hope that I was of assistance,

-Rill

sorries

I do think that Blast-line bombs are fun and useful. And Nitronome is the easiest of them. But I don't recommend Nitronome to novice bombers, because managing the knockback can be difficult. So they end up doing poor DPS and annoying their teammates.