Imho it doesnt really matter if you are evade, dmg etc.
My decision process for forming a 220 hard...
1) good high level DD (soldi, agent, MA, Shade etc)
2) Good High level DD
3) Solid high HP tanking profs
4) Some sort of heals (keeper aura, high lvl advy, Fixer HoTs, Doc, MP)
5) Good High level DD
6) Crowd control
7) XP stick/pet profs
So high levels are a must. If i get good Highbie shades, soldi and enf I am more relaxed about letting a 205 in. Sub 200 generally no. Usually slower RS so they get to the mobs late, Any agg = insta death, Generally team members will be reluctant to do a hard if there are lower players and generally do little DD (few exceptions, but generally too few to be worth the risk)
My decision process for a 220 easy
1) some Medium to high level DD
2) Some medium to high level team buffers (MP, Trader, Fixer, Keeper), they can supplement lower skill levels and DMG and compensate
3) Some Medium level higher HP/Pet profs/CC
4) anyone medium level
5) Last player to fill spot that would otherwise be empty.
Again the first 3 players in the team will dictate the last 2 players into the team. If i can get 3 players all around 210 and over then the last 2 spots could be filled by naked MA NM Docs for all i care. The top 3 DD's will do 3x the dmg of anyone else anyway. If the first 3 players are more support profs then the last 2 need to be semi-decent. However, if there are plenty of 200+ players they will be invited before sub 200. Its just the fact that they have more HP, do more DMG, die less, have better buffs and are faster. There are exceptions to the rule but they are few and far between. I will however recruit a lowbie because i know them (org mate, friend of roller etc).
The main reason why your gear doesnt really count is that i've never interviewed someone low before i recruit them... "what weaps you have", "what armour you got", "how much DPS do you deal" etc etc. And i've never been asked either. I grab and go and if they are in the 10% that has nice gear then great, if they are in the 90% that doesnt then that was the risk i took when i recruited. I've also NEVER kicked anyone because they were low and werent doing super DD. I personally think it would be cruel to ask someone all about their DD, buffs, HP etc and then not recruit them because of it. I would NEVER join a team that would ask me to present my case to join either.
In any DD i have seen for inf easy mish number 1&2 combined will be more than the rest of the team combined so one player doing 7% more dmg will be superfluous.
I think the main thing you can do as a lowbie to help out is
1) get to the mish quickly, no running from Pen etc
2) get around the mish quickly (fixer will be fine)
3) dont go afk EVER, its the only thing i ever kick ppl for, that or blatant stupidity/hate etc. You were invited to help you out so dont be rude and not do everything you can do
4) do what you can do well, without fuss (fixer, buff RS, HoT's long and short, NCU etc you know what you can do

)
5) dont die every 5 seconds (avoid alphas, be the last one into the room, wait for CC's to do their job and have assist macro)
I think that goes for all players regardless of profession.