So should I cut the triangles first or directly glue and sand them. My main concern is regarding the wings curvature.. Will it be able to create the low pressure high pressure zone as of an real plane wing.

You can directly approach KK Sir for any query related to planes. He is one of the most Senior members in this domain. One can get a lot from him.

I am moving ahead to tails. Have made a plan. Attaching the side and top view of the tail I thought of. Suggest if you have any other thoughts on this.