forgive my bad English

1st

I saw low rating clubs at 1st-2nd of the league and win against higher rating teams when i look closely i noticed most of their main squad if not all same nationality dose that count for somehow the lake of 4*-5* star players even against same tactic for eg: 4-4-2 against team made of 3-5* while his best player 3*

2nd
what is better for player progress playing friendly match or do the training at hard regardless of income and booster packs

3rd
how can i know player is fast trainer read in some articles if his market value worth 30x salary then he will be good player at lower level as mine level 3 now which give me the right clue what should i look at

many thanks in advance