Fun fact: apparently, the original (and now obsolete) meaning was actually "family" (https://en.m.wiktionary.org/wiki/фамилия).
In the meantime, "family" got a suffix and became фами́лия + -ный (https://en.m.wiktionary.org/wiki/фамильный#Russian).
yes and so is the pronoun proceeding it. once I learned the case endings and learned to identify them Russian became much easier to read (feminine accusative: U/YU
I particularly liked this one, which was posted by someone else in another excercise: http://www.russianlessons.net/grammar/nouns_nominative.php
The other cases are linked on the page.
Dnagashi's linked site is great for explanations. For quick reference, I prefer https://en.m.wikipedia.org/wiki/Russian_declension. Even quicker and as a handy, light and laminated sheet that can be carried around during commuting: https://de.pons.com/grammatik-wortschatz/pons-grammatik-auf-einen-blick-russisch-978-3-12-561908-1/russisch. You don't need to understand German to use it.
It includes declination tables of nouns, pronouns, adjectives, prepositions - these definitely don't require knowledge of German. It also includes explanations of verbal conjugation - I think you can only use those if you understand German, or already know the Russian rules and are using the cheatsheet for reference. Same goes for the included information on word order in different types of propositions (affirmation, negation, interrogation), the info on numbers and the translation of conjunctions.
Size: 3* double-sided A4 sheets. Cost: 5€ (worth every cent :)
-ный is a suffix that is tagged on to convert a noun/ verb into an adjective. The alternative form - used when the ending is stressed - is -но́й.
Variants occur in certain cases:
When the stem ends in a velar/ ц -> palatisation.
"A stem ending in -л turns into -ль before the suffix; contrariwise, all other stems ending in -ь lose this."
Special rules concerning change of stress [that I'm not ready to deal with yet].
The list of Russian words with the suffix -ный is gigantic. So it's probably quite a good idea to learn the declension table by heart https://en.m.wiktionary.org/wiki/-%D0%BD%D1%8B%D0%B9#Russian.
The stressed form has less words.