So as my recent birthday present I got the remaining DLC that I was missing ( Broken Steel, Point Lookout and Mothership Zeta )
And I was curious as to what level to try and tackle these at since I've started a new game, I'm currently LV.9 and just made it to Rivet City.
If they are anything like The Pitt I think I should chance them at Lv.15+ ?

You should load them all right away. I don't have MZ, but in PL enemies automatically do more damage to you, it's built in , so watch out. Level 26 and Reavers everywhere I go in the PL... everywhere. Just bring weapons and ammo... a lot.

Small guns 50
Chinese AR with 1000+ bullets and condition is in the region of 60% - 75%
will that suffice ?

That will do very ell against anything in most of the DLCs...

i like to bring my railway rifle to shoot the weapon out of there hands and my gauss rifle or lincolns repeater to PL.
MZ is a liitle confusing finding things imo. but you defiinately need a powerful weapon and a weapon like the dart gun to slow down the creatures in PL.
have fun.

First, level up and complete the other DLCs, when 15+ I'd say continue the story and finish Broken Steel, then Point Lookout (it's medium difficulty, depending on what level you are, it will go harder) and finally Mothership Zeta (which you wanna touch at the last because it is a crazyness to destroy the aliens.

Pff. I took on MZ at level 9. Honestly every enemy in the game scales to your level. Some are set to be lower level than you, others higher. There is no real difference in difficulty throughout most of the game in almost any place, with the exception of what kind of gear you bring with you.

Basically, a great weapon and great armor make the whole game easier.

if i was to do it over i would do operation anchorage, MZ, the pitt, point lookout, broken steel in that order.