I didn't get what I was looking for so I went searching and found what I wanted. As you will see the verb servir is often used for 'usefulness' which I was getting at. Now I can share with others.
Yes, in casual conversation they are almost always perfectly interchangeable. Utilizar is more formal, and there will be occasions when there is a preference for one over the other, but they will both be understandable, regardless of which you choose. Usar is more casual. I don't feel like looking it up, but I believe it is a case where Spanish speakers took an English word (use) and utilized (: it as Spanish.
Yes. Usar = to use. It seems like the English word for "to" is being used twice as in "go to to use" but this is not the case. The structure is like this; You (Usted) are going (va) to (a) use (usar) la (the) spoon (cuchara). Remember English and Spanish are not the same language and will not have exact 1 for 1 correlations with grammar. The use of "va a" is literately "it goes to" but that is not the intended meaning in Spanish. We use "going" in English very loosely, as it could mean the present or future. As in "I'm going now" or "I will be going tomorrow." In fact I can even say "I was going to go yesterday." In Spanish, I believe we only use the "ing" form for things that are happening right now. But that is a different topic. Here we use the structure: [Subject] (like yo, tu, usted, etc). + IR (conjugated for the subject in the present tense) + a + INFINITIVE SPANISH VERB. This means "going to do something" and is an easy way to talk about some thing that a person is going to do in the future only. Here are a few more examples. I'm going to sleep. = Voy a dormir. Are you going to play? = ¿Vas a jugar? They are going to eat. = Ellos (or ellas if all female) van a comer. We are going to arrive soon. = Vamos a llegar pronto. I hope this helps and is not too long of an explanation. It looks like you are on your way to becoming a polyglot with the German, Spanish, English and Italian. That's impressive. I'm curious, what is your native language?