1) an increasing number - it is a number that is increasing.
increasing - participle I
2)more warm and friendly - more refers to both adj.
if you say "more warm and frienlier" it sounds strange,
warmer and friendlier is better then. I think, if only it is possible you should use the shorter form, so "warmer and friendlier" would be my answer.
3) why clumsy?
not to - a very strange imperative; I haven't met it so far.