Yes, angles in Construct and directions in MMF are different.
Here's the basic breakdown:
If you make an animation angle for 180, then when your sprite is facing 180, it will use that animation angle instead of just turning the sprite. Construct chooses the animation angle closest to the actual angle of your sprite.
If you only have Angle 0 drawn, then Construct will manually rotate your sprite around 360 degrees.
If you have animations for 0, 90, 180, and 270 then Construct will pick the closest one and show that sprite, but it will manually turn it the rest of the way:http://files.getdropbox.com/u/529356/angles.cap
If you set the sprite to "No rotation" in the properties, then it won't turn between angles, and the sprite will "snap" to whatever the closest angle is. Go ahead and try it out.
There are more animation and angle options too, mess with them a while and see what you can come up with. Construct might look a little like MMF on the surface, but it does work differently, so you're going to have to unlearn some old MMF habits if you want to switch over.
Anyway, you really should invest in a graphics card, it's pretty much necessary
for making games with Construct. You're going to run out of onboard VRAM really quick, and the layout editor will crash on you, and you will have all sorts of problems. You won't be able to load and run other people's .caps and you'll be pretty much stuck for how much you can learn to do.
Not to mention you'll be asking a lot of questions that are easily answered in the tutorials, and people will just keep telling you to go look at the tutorials.
A cheap $40 graphics card from five years ago is enough to work on most stuff, and it's a good investment.