Relative to each other...:
The Afuris have a lower base damage (14), firing rate (20.0), and reload speed (2.7 s), but also have a greater magazine size (70 rounds). The Afuris would most likely benefit from damage, reload speed, and fire rate mods.
The Twin Vipers have a lower magazine size (28 rounds) and reload speed (1.9 s), but also have a higher base damage (16) and firing rate (25.0). The Twin Vipers would greatly benefit from magazine size mods and probably reload speed ones as well (to offset the reload times).
Both of these weapons have the same accuracy (8.7), max ammo capacity (210), and critical damage multiplier values (150%). Plus, as you stated, both have a terrible rate of ammunition efficiency. They do have some armor penetration issues though, so keep that in mind.
Overall, the Twin Vipers have a greater base max damage potential (3,360) compared to the Afuris (2,940). Yet, the Afuris have a greater base damage per magazine (980) compared to the Twin Vipers (448). You'll be burning through each magazine on the Vipers much faster, necessitating more reloads. Do you need sustained and quick (burst) damage? Go for the Afuris. If you need long-term damage, go for the Twin Vipers. Personally, I say choose the Twin Vipers but, make sure to slap on some magazine size and reload speed mods.
Unfortunately, as of Update 10.2 or 10.3, the drop tables have been encrypted. So, you cannot determine specific percentages of drops. However, as the Warframe wiki has indicated, each boss has a unique item which can be only dropped by them. Moreover, each of three factions has a tendency to drop certain mods and crafting materials over others.
Hopefully, this issue will be alleviated when the codex gets released...
EDIT:
I think there was an earlier version of the drop table released by creative crackers around a few weeks ago, but, it probably has become outdated with the recent patches.
Best Answer
Yes, it possible to do so. Though, it's really not recommended due to the resource costs involved.
To make (or access) the dojo itself, you must first create or join a clan. Then someone needs to make the Clan Key (the blueprint of this will be added to the player's foundry once they join a clan). The resources required are the following:
Afterwards, the basic Clan Dojo, with a basic Clan hall as the starting room, is created. Now, resource costs for building other rooms (connectors, reactors, research facilities, etc.) are scaled depending on what clan size bracket you fall into (in this case, your supposed clan will fall into the Ghost Clan bracket - 1-10 members in total).
Yet still, they are quite expensive for a small number of players to handle, especially due to the usage of "rare" resources at higher levels (such as Forma). Unless you have a large stockpile of resources and credits, it's suggested to have at least 4-6 members to build a basic dojo with the important facilities. But, it's certainly doable with 1-2 people, though not recommended.
I strongly suggest you pay a visit to the Warframe wiki page on Clan Dojos for more information on each room type's costs, as well as for pre-planning the layout. Remember, you don't want to waste resources destroying and creating more rooms than necessary!