You are almost there. When using a demonstrative adjective/determiner, the word (этот/это/эта/эти) would need to agree with the associated noub in gender and number. When using a demonstrative pronoun, on the other hand, there is only one form -- это. So, это can be either a demonstrative adjective or a demonstrative pronoun.
I'm very new to this but based upon observation, the case seems to be that "ем" (yem) is conjugated to "я" (ya, first person "I" in English) while "ест" (est) is conjugated to "Он/Она/Оно" (On, Ona, Ono) because it conjugates to the subject, "Том" (Tom) in a third-person conjugation
Since Russian verbs are being introduced, I would like to know. How does an infinitive look like? Is there a pattern that can be applied? [Yes, I understand that irregular verbs may have exceptions.]
Spanish (infinitives end in "-ar", "-ir" and "-er") Saber (Infinitive of "to know") I know - Yo se, You know - Tu sabes, He/She knows - El/Ella sabe, We know - Nos sabemos, They know - Ellos/Ellas saben
French (infinitives end in "-er", "-ir" and "-re") Manger (Infinitive of "to eat") I eat - Je mange, You eat - Tu manges, He/She eats - Il/Elle mange We eat - Nous mangons, They eat - Ils/Elles mangent
German Haben (Infinitive of "to have") I have - Ich habe, You have - Du hast, He/She has - Er/Sie hat We have - Wir haben, They have - Sie haben
3) I looked up the verb conjugations for common Russian verbs. What are the infinitive ending(s) for Russian verbs? When is Вы or Ты used?
Know | I know - Я знаю, You know - Вы знаете, He/She knows - Он/Она знает, We know - Мы знаем, They know - Они знают
Eat | I eat - Я ем, You eat - Ты ешь, He/She eats - Он/Она ест We eat - Мы едим, They eat - Они едят
Russian verbs have three common infinitive endings: "-ть", "-ти", "-чь" Examples: "-ть" (есть - to eat, знать - to know) - the most popular ending "-ти" (идти - to go, нести - to carry) "-чь" (печь - to bake)
Also, there are reflexive verbs (verbs whose direct object is the same as its subject). One adds additional "-сь" to the standard endings using such verbs, e.g.:
мыть - мыться (to wash - to wash oneself) стричь - стричься (to cut hair - to cut one's hair)
Вы - is the plural form of "you" (also used as "polite" singular) Ты - is the singular informal form of "you"
These pronouns are very close to "vous" and "tu" In french