The harshness is something everyone went through I think. Here's one thing to consider - PG, it's hard on your throat and for that reason some like to use PG/VG mixes and some (like me) prefer pure VG juices. One thing I will say is that the harshness will subside. The first week or two will be difficult but it will pass. You don't have the anesthetic type chemicals in
vaping that you do in real cigs. I went from smoking a lot of rollies a day to vaping and found it very tough on my throat.
I had a 510 for my first e-cig as well and I had your problems to the letter. I will give you a little advice that I hope will help!
The 510 is a small unit and will heat very quickly. Remember to give the atomizer time to cool. Use it too many times too soon and it's painfully hot!
I found the 510 is extremely temprimental to drip with. I will put 3 drops in a clean atomizer and it will simply disappear. I find I need 4 - 6 drops on an entirely clean atomizer and give it time to filter away and then another drop or two. For something so small I honestly wonder where it all goes. My advice to you is not to blow the atomizer out if it creates little vapour. It is simply flooded. Tap some liquid out of the top and vape off any excess (unless it is truly satturated then you will need to blow it out). Once there is liquid "inside" the atomizer it will be easier to just use one or two drops per vape. First fill up on a 510 is always the hardest to get right. Too harsh or too wet. Once you have the balance, just two drops and you'll be golden.
If there is too little liquid around the heating coil then it's just a blast of very hot air with a little vapour and it's very painful! I'd say overfill it slightly first and keep vaping until there is decent vapour then just top it off. It should be a cooler experience.
Consider a new inhalation technique - instead of breathing straight into your lungs, take the vapour into your mouth first and then inhale. It will give the vapour time to cool and should help you especially in the beginning. Direct inhaling still kills my lungs and throat. I'm so used to vaping into my mouth then inhaling I don't even think about it.
Still on inhaltion, try not to drag as hard as you would on a real cigarette. You should have a lighter draw for longer. The atomizer needs time to create vapour.
For the vapour issue, straight PG has the least amount of vapour from it. PG/VG mix or straight VG will produce more "smoke". I was skeptical about this at first but I tried VG and sometimes I think it's too much to use VG in public because it is a lot more vapour. Some PG liquids will also not make much, it's simply the blend of the juice. Some of my PG juices are comparable to VG and some will just never make a lot which I love for public use at times.
For flavours, your taste buds will start working again in time. I started on tobacco flavours and left my "other" flavours to one side for a while then tried them 3 weeks in and then I could really taste it.
One thing most people will not say because they did it differently - I actually did not remove anything from my 510 to drip with. I found it holds the liquid better with the wick still there. You may want to consider a "tank" style 510 atomizer. It's less hassle. I can't speak for the 510 tank's performance but I got an ego tank and it's been a godsend compared to the 510. The flavour is a little muted but for the convenience of not having to fill for so long is amazing. I also still drip with my 510s when I am at home.
I really hope you stick with trying vaping. It is a bit of a learning curve at the beginning but I can tell you it will only get better. All the best and good luck!
my friends who have tried my eGo (heavy smokers like I was) was blown away at the fact that it was harsher than anything they smoked haha! but keep at it, you wont regret it! I'm actually looking to try some 70/30 pg/vg mix with my next order which will be from freedomsmokeusa.com 
