Recordar is transitive and always needs a direct object - "Yo recuerdo algo." Acordarse is intransitive and doesn't need a direct object - "Me acuerdo." If you want to add a direct object to Acordarse, you must use "de" - "te acuerdas de algo?"

Better use a dictionary. It's quite long to explain. The dictionary has good examples.

I find it helps to do litreral translations and say them to your self often in place of the grammatical english phrases. For example, start saying "from where are you" instead of "where are you from" or "I have hunger" instead of "I am hungry". That keeps the sentence structures and phrases fresh in my mind.

Some verbs like acordar must be followed by "de" when there is a direct object as Juicy_Maffews explained above. Other verbs that also follow that rule are listed here: https://www.thoughtco.com/verbs-followed-by-de-and-an-infinitive-3079236

Totally agree ,what a load of crap

The subject "you" is implied by "tienes" and acordarte is a form of the infinitive reflexive acordarse with the te at the end indicating the verb is being done to "you" (informal/familiar). It is left at the end of the verb because you want to keep the inifinitive form since it follows the conjugated form of the verb "tener."

That was my first thought. We must be older than the Owl to know that.

Here's looking at you kid!