3D sketching

Yes for both.

Bharath yes you can use a fillet and chamfer in a 3d sketch just like in 2d. The only thing you have to be careful is if you do a sweep along the 3d sketch if the profile you are seeping is to large and your fillets and chamfers are to small this could give you an error in your sweep.

Beware that fillets can make the straight line geometry difficult to change. Fillets often flip into cusps and blow up subsequent geometry. Solidworks does not seen to know the diffterence between fillet tangency and cusp tangency.

Fillets and lines combine to make excellent paths for exhaust pipes and other complex tubing shapes.