Some questions I have

Hello I am an 18 Year old guy and I have some questions about my skin that I guess I feel kind of embarassed to ask in real life since I am and guy and all, but I really want healthy looking skin so here we go hehe,

alright first off i was wondering why before I exercise my face always looks so dry and "old".  I mean sometimes it even looks like a wasteland if you know what i mean.  However when I start exercising or doing some physical activity, my face starts looking smoother and younger? Also my skin look so much when I am in the sun.  I really don't know how to get smooth skin without having to sweat.  I have just started a month or so exercising alot, I first lost alot of weight 3 months ago (via alot of running), now I am working out most of the days of the weak.  Could this change be bringing this old look to me?  Btw I found out I have really low blood pressure if that means anything, hehe trying to throw everything out that I can.

2nd question: I find constantly that I have dandruffy skin under my eyes (which also has circles due to my high school career of lack of sleep), this dandruffy stuff also is on my eyelashes in the morning.  Is there any remedy for this? and why do i have it? 

3rd question: above my nose and under my eyes (where the circles are), the skin is not "smooth" but rather theres some higher bumpy skin, but it isn't white so I don't think it's white heads, what are these things and can I get rid of them? they look a little oily at times.

Last question:  What foods should I eat for more healthy looking skin?  Also I heard steaming or forcing alot of sweat helps for more healthy skin? THanks alot!