Superlative x Comparative

Theory
http://esl.about.com/cs/beginner/a/beg_compsup.htm

Games
https://learnenglishkids.britishcouncil.org/en/grammar-games/comparatives-and-superlatives

Exercises
http://www.englisch-hilfen.de/en/exercises/adjectives_adverbs/adjectives_comparison_sentences2.htm
http://www.ego4u.com/en/cram-up/grammar/adjectives-adverbs/adjectives/exercises
http://www.usingenglish.com/quizzes/45.html
http://www.eclecticenglish.com/quizzes/ComparativeQuiz/comparativeQuiz.html
http://www.learnenglishfeelgood.com/english-comparative-superlative1.html

Superlative

http://www.englishexercises.org/makeagame/viewgame.asp?id=1876
http://www.learnenglish-online.com/grammar/tests/superlativeadjectives.html
http://speakspeak.com/english-grammar-exercises/elementary/superlative-adjectives
http://www.tolearnenglish.com/exercises/exercise-english-2/exercise-english-29600.php

Comparative

http://www.englishexercises.org/makeagame/viewgame.asp?id=2596
http://www.learnenglish-online.com/grammar/tests/comparativeadjectives2.html
http://www.better-english.com/grammar/comparatives.htm
http://www.englisch-hilfen.de/en/exercises/adjectives_adverbs/adjectives_comparison_sentences.htm

Adjectives x adverbs of manner

Adjectives characterise a noun : "She is intelligent. ". I am giving a characteristic to the woman (she).

Adverbs of manner characterise a verb: "She writes well". I am giving a characteristic to the way she writes.

Exercises
http://www.englisch-hilfen.de/en/grammar/adverbien.htm
http://www.ego4u.com/en/cram-up/grammar/adjectives-adverbs/adjective-or-adverb
http://www.ego4u.com/en/cram-up/grammar/adjectives-adverbs/exercises
http://www.ego4u.com/en/read-on/countries/usa/tour/niagara-falls#exercises
http://web2.uvcs.uvic.ca/elc/studyzone/200/grammar/adjadv1.htm

Game
http://www.eslgamesplus.com/adjectives-adverbs-ly-rally/

Adjectives

http://www.manythings.org/vocabulary/games/b/words.php?f=adjectives_for_people_1
http://www.manythings.org/vq/mc-adj.html

Adjective order 
- Theory and exercises https://learnenglish.britishcouncil.org/en/english-grammar/adjectives/order-adjectives
- More exercises
http://www.learnenglishfeelgood.com/esl_adjectiveorder4.html
http://www.englishexercises.org/makeagame/viewgame.asp?id=6877
http://www.usingenglish.com/quizzes/139.html