When I feel like a drop isn't hitting hard enough usually the first thing I do is add a bar of silence/end the build earlier so there's a bigger contrast.  Almost always helps.  Like Bryan said, contrast is key.

It's probably catchy, you've probably worked on it too much, and it could be good but it definitely could be crap.

I have this happen to me all the time, I'll have the chorus to a song I've been working on playing on repeat in my head as I'm trying to sleep. Drives me insane.

You could always try writing something on your Facebook asking if any singers are looking to collab. I managed to find some people this way recently, both friends I had who I didn't know sang and friends of friends who got tagged.

You should try doing some vocals yourself too!  Even if you don't think of yourself as a great singer or songwriter you can get it sounding pretty good by layering takes and lathering on the autotune.  I think producers often think of singing as this totally alien talent, but anyone can do it.

its the baseline and melody that make the track, so these are the most important, you need a baseline and melody catchy enough that people want to listen to it over and over again..

This seems incredibly subjective, varying depending on your taste and what kind of music you're making.  This could totally be true for you and the type of music you're making, but I don't think it's going to apply to everyone.  In many cases the percussion and groove is actually far more important than the melody or the bass line, particularly in more underground genres like techno or tech house.  I tend to write music with vocals, so I'm usually starting with a chord progression and the vocal lines before introducing other melodies or the bass line. 

I like to start with whatever I'm going to think of as the "core" of the song.  If that's a vocal track, that's going to be the chorus.  Usually for those I start with a chord progression, and then write a vocal melody and words to that, and then build everything else around those.  If I'm making an instrumental track, I also tend to like to start with the chord progression I'm going to use on the drop, but from there I tend to move to percussion and from there to any melodies.  I like to try and build up a few parts from there, the chorus or the drop, and then a verse section, and start to try to build a rough outline of the structure of the song.  Once I have a structure I think flows well (Side note, I think this an incredibly important step that a lot of people overlook, designing a cohesive structure that makes sense is one of the most important things to making a song sound good) I work on more of the detail elements - drum fills, risers, fx, etc.  I tend to mix as I go along, which is maybe a bit unorthodox and/or lazy but it seems to work for me.