Grip: Same grip for both shots.
Stance: Same stance for both shots
The contact point will vary depending on what you want to do on any given ball. Obviously if you are deep in the court with a ball around your knees you probably aren't going to be trying to crack a really hard flat forehand for a winner. However, if you are a foot inside the baseline with a sitter around your shoulder height you are probably going to want to be pretty aggressive with this shot and really hit through the ball.
For me, the best way to learn to hit these shots is to understand swing-paths. If you are looking to hit topspin you want to start well below the ball and hit up through the ball and finish high. There is a more advanced technique for generating topspin called the windshield wiper but you should NOT worry about this technique at your current level.
For flattening out a ball and hitting a penetrating and aggressive forehand your swing-path should be much more horizontal than before and focus on really driving through the ball more. This means that your racquet is general going to start level with the ball and if you take my scenario from the first paragraph and input it here, your finish should be roughly around or near the top of your shoulder since you were hitting a ball at shoulder height.
When you get this concept down then you literally have an infinite amount of shots you can hit since you understand that a vertical swing-path is giving you spin on the ball and a more horizontal one is hitting through the ball. You can vary the amount you hit through the ball and vary the amount of spin to whatever degree you want.
Spinning the ball in with a good amount of topspin but not getting the pace and depth you want? Go more horizontal and through the ball.
Hitting the ball too flat (and long) and not getting margin of error to keep up your consistency? Swing more vertical and brush the back of the ball more.
I'm a pretty young player (only 20 although I play at a pretty decent level) so take my teaching for what it is worth.
(2) Head i.Prestige Mid 13.1oz 8PTS headlight. Now strung with Luxilon Big Banger ALU Power 16L string at 53#'s.