main road I travel on every day to get to work was resurfaced about 6 months ago by contractors who I can only assume to have either been cowboys (no disrespect to y'all good souls down in Texas! ) in their trade or have a standard for measuring road smoothness like hairy ar**d foundrymen. Instead of what you would expect from a newly surfaced road, of a beautifully smooth and quiet stretch of road a joy to drive our lovely BM's on, these guys decided to save a bit of dough by skimping on the tar that holds all the stones and surface together. As a result, the surface is as noisy as heck and has been falling apart from the day they finished ... with stones of upto an inch in size that are so loose that they get throw upwards and backwards by the tyres from any vehicle which is on the road ... and if you happen to be a normal distance behind someone it can mean smashing your windscreen when you're travelling at 50-70 mph. Not a nice experience I'd like to add! My windscreen has been smashed twice in this time and replaced 3 times (the last time because it wasn't sealed properly also).
In answer to your question about the gap between the bottom of the glass and the metal, yes it is normal to have a small gap there of about 1cm. You should have a couple cylindical rubber spacers (about 1cm diameter, surprisingly) in this gap that the screen rests on as the sealant cures.
A couple things I noted while my screen was being replaced:
1) The little black plastic fasteners (about 10 of them) that hold the 2 plastic covers just under the wiper blades just suck when it comes to good practical design, surely BMW didn't design these?! They are very brittle and once clipped on, there is almost no way to remove them again without breaking the little buggers. Mine had to be ordered from Germany and took about 2 weeks to get here ... meaning I had to drive around with those panels rattling and whistling at higher speeds. Has anyone tried to use an alternative type of fastener, like a twist-lock type?
2) Sealing a windscreen can be tricky. If you do get any unwanted wind noise in the cabin, you can check the seal by running a flat piece of metal (I used a key) from inside the car all around the inner edges of the screen where it should be sealed with the rubber compound. If it is sealed, your key will rub on rubber. If you hear a metal-on-metal sound, it's not sealed properly.
Just a final note on safety. The windscreen should be sealed properly as it is designed to give structural strength and rigidity to the car. If you think it has been poorly fitted I would recommend you get the fitting firm to refit it.
Regards,
Masood