(1.) с тобою или с тобой - Sometimes I see this show up and I'm confused when to use which. Is it a poetic thing like чтоб/чтобы и хоть/хотя or does it go with something?
Meanings of all these couples are the same but the style is somewhat different.
с тобой - Normal literary.
с тобою - Acceptable in poetry (to fit the rhyme and meter)
The same is for all -ой and -ей nouns and adjectives (in Instrumental, feminine)

чтоб, хоть, опять - Colloquial
чтобы, хотя, снова - Normal

(2.) So I've been listening to the song "седая ночь" by Yuri Shatunov. And there's this line that comes up "Мне одному совсем, совсем ни к чему" and I would guess that this translates to "I'm alone not quite because of this." I could be wrong, but could someone unravel the grammatical situation & the meaning here because I don't get it lol. I've seen к чему quite a few times.
"I don't need it at all, at all, if I am alone."
"ни к чему" is a phrase. "<Someone in Dative> + <Something in Nominative> + ни к чему" = Someone does not need Something.

Literally: To Someone Something (is not needed) for anything

Мне это ни к чему. = I don't need it.
(3.) Using "то" in the middle of sentences when and why to use it?
It has many meanings and ways of usage. Most often it is "then" in "if-then" construction.

(4.) The verbs for touch -- what are they?
My dictionary gives overall 28 different meanings of this English verb in 3 supergroups. For each meaning several Russian synonyms are proposed.

(5.) What are some examples of using подсказать?
To prompt, to hint.
"Не подскажете, как пройти на Северный Полюс?" Will you, please, tell me how to get to the North Pole?