You smoked for over 13 years, long enough to damage your tastebuds. Most new vapers who were smokers have what's termed as "Vaper's Tongue" -- a decreased ability to taste. Your tastebuds on your tongue will heal, but it will take time.
Meanwhile, there are a few things you can do. Practice good oral hygiene; brush your teeth/gums/back of your tongue. Drink plenty of water because vaping can cause dry mouth, increasing your chances for vaper's tongue. Chew gum or suck on hard candy to promote saliva production.
While vaping, exhale some of the vapor out your nose. Our sense of taste is closely tied to our sense of smell.
The following posts should prove helpful for you:
Headache from vaping is generally caused from too much nicotine. Try lowering the nic concentration.
For e-liquid, the typical nicotine recommendations are as follows:
1/2 pack per day or less = 6 mg nicotine
1 ppd = 12 mg
1 1/2 ppd = 18 mg
2 ppd = 24 mg
Figure on consuming at least 2 - 3 ml of liquid daily. Bottles are usually 10 or 30 ml volume.
PG and VG are often used together in different ratios in e-liquid. For example, a 50/50 PG/VG ratio. Many juice vendors offer a range of different ratios as far as PG/VG.
E-liquid generally has concentrated nicotine, propylene glycol (Pg), vegetable glycerin (Vg) and flavoring extracts.
The ratio of Pg to Vg is known as the pg/vg ratio, and a 50/50 blend is common.
PG = Propylene Glycol - the "flavor carrier" of e-liquid. A secondary source of "throat hit", but not as strong as the nicotine concentration. Some people have a sensitivity or even an allergy to PG. It's very thin in consistancy.
VG = Vegetable Glycerin - the "vapor maker" of e-liquid. Used as a sweeter in many food sources, and also as a skin emollient. It's very thick in consistancy.