I cleared 10 acres of similar property last year. After cutting and bucking all the trees, I hired a large excavator with experienced operator to pull the stumps and large rocks. He also buried a few rock walls for me, and created a long ramp into the back of my barn. Nothing like a real excavator to get things done fast.... he was done with the excavator in around 7-10 days of work time. Note he couldn't work in bad weather or mud, so total elapsed time with the excavator was around a month.
I waited around a month for things to dry out, then burned all the brush piles and tree limbs that I didn't cut for firewood. There were a few good hardwoods that I took to the lumbermill to cut for flooring and siding.
After the excavator was finished and the brush was burned, the excavator operator brought in a D-8 bulldozer to run over the entire acreage, pushing all the stumps and large boulders into a long windrow at the back of the property. The D-8 took 2-3 days and left us with a very smooth and fairly compacted surface.
I then ran a Harley power rake over the whole thing a few times after the D-8 left, and seeded with a mix of bluegrass, orchard grass, and white-flower clover.
A year later, I've had to pick out a few medium sized boulders with my backhoe that seemed to rise out of the ground, and fill in a couple of erosion areas, but other than that, I have a gorgeous relatively weed-free pasture that our horses cannot keep up with. The windrow has completely grown over with the natural vegetation that was in the area. We left a handful of large specimen trees so the horses would have some shade in the summer, and they look very nice in the midst of all the green pasture.
Many people told me that it should take around 3 years for a pasture to fully grow in, but ours is very thick already; I have to mow at least every 2 weeks, and sometimes weekly to keep it down.
We have another 10 acres of woods behind the pasture that backs up to a pond on the other side. Once the leaves fall and the ground starts to freeze at night, I'll start working on cutting all the trees down. The first 10 acres of clearing were started in April of last year, and it wasn't a lot of fun cutting down and bucking trees in the muddy wet leaves, and the heavy equipment sometimes had a hard time in the mud. The work should be a lot easier and go a lot faster in the cooler and hopefully drier weather.