New user to Forge...have a few questions regarding Quest

I was directed to Forge through a post on Reddit and after taking a gander at the screenshots, realized that this program is exactly what I was looking for to get my MtG fix as well as help with deck building. I played the original MtG PC game and have wished for another like it to come out for a long time.
I've managed to finally install and get most of the Forge to work, aside from the pictures aspect. Although now that I've done a little more digging on the forums, I realize that I can take a few more steps to getting the pictures the way I want them to be. There are a few things that I've run across that confuse me and haven't figured out how to change or what options to use.
During the quest mode, when I am battling my enemies they have 20 life and I only have 15. Is there a place to change this at? I looked around but couldn't find one. Also, is there a way to change the mulligan rules?
When deciding on how to start a quest, I know that most of those options are personal preference, but I'm suffering from "too many options syndrome." I read through the forum post on what each of the options does but I'm just wondering if someone could give me a few tips on what would be the best options to pick for someone who was always a casual player and not so good at deck-building. Which brings me to my next issue...
I've been playing around with the options on starting a quest as well as building a deck, and I've only managed to build a few so far, but I've only managed to win 1 match against the easy AI. This could be due to my opponent choice, but I will blame it more on my lack of deck building skills. I tried making a R/W deck and a G/W deck, but both of them have come out lackluster, I can't seem to get the mana curve down properly and have managed to mulligan my way to about a 4 card opening hand. Suffice it to say, I didn't win that game. I'm trying to figure out if it's better to have my opening selection of cards be specific colors, or if I should just do better with picking my cards. (I realize that could be answered yes to both questions, lol
) Also, I'd love to know if it's better to have a 40 card deck or 60 in the beginning.
Thanks in advance for any help you can give me. Even if you can give me links to read up on and study, I'd be glad to do so. I have played most of the Duels games on the computer and do fairly well against other players and the AI, but I'd actually love to improve my deckbuilding skills
I've managed to finally install and get most of the Forge to work, aside from the pictures aspect. Although now that I've done a little more digging on the forums, I realize that I can take a few more steps to getting the pictures the way I want them to be. There are a few things that I've run across that confuse me and haven't figured out how to change or what options to use.
During the quest mode, when I am battling my enemies they have 20 life and I only have 15. Is there a place to change this at? I looked around but couldn't find one. Also, is there a way to change the mulligan rules?
When deciding on how to start a quest, I know that most of those options are personal preference, but I'm suffering from "too many options syndrome." I read through the forum post on what each of the options does but I'm just wondering if someone could give me a few tips on what would be the best options to pick for someone who was always a casual player and not so good at deck-building. Which brings me to my next issue...
I've been playing around with the options on starting a quest as well as building a deck, and I've only managed to build a few so far, but I've only managed to win 1 match against the easy AI. This could be due to my opponent choice, but I will blame it more on my lack of deck building skills. I tried making a R/W deck and a G/W deck, but both of them have come out lackluster, I can't seem to get the mana curve down properly and have managed to mulligan my way to about a 4 card opening hand. Suffice it to say, I didn't win that game. I'm trying to figure out if it's better to have my opening selection of cards be specific colors, or if I should just do better with picking my cards. (I realize that could be answered yes to both questions, lol

Thanks in advance for any help you can give me. Even if you can give me links to read up on and study, I'd be glad to do so. I have played most of the Duels games on the computer and do fairly well against other players and the AI, but I'd actually love to improve my deckbuilding skills