Ich will das T-Shirt vorbestellen.

No. In German, will is the 1st person singular form of wollen, which means to want.

So:

• Ich will ... = I want ...
• not I will ... in the future sense

To talk about the future in German, you usually use werden, or very often just the present tense if the context is clear.

Examples:

• Ich werde das T-Shirt vorbestellen. = I will pre-order the T-shirt.
• Ich bestelle das T-Shirt morgen vor. = I’m pre-ordering the T-shirt tomorrow.

Because will is a modal verb. In German, when you use a modal verb like wollen, the other verb usually goes to the end of the clause in the infinitive form.

So the pattern is:

subject + modal verb + object + main verb at the end

Here:

• Ich = subject
• will = modal verb
• das T-Shirt = object
• vorbestellen = infinitive at the end

That is why the sentence is Ich will das T-Shirt vorbestellen.

Because after a modal verb like wollen, German uses the bare infinitive, without zu.

So you say:

• Ich will das T-Shirt vorbestellen.

not:

• Ich will das T-Shirt zu vorbestellen.

Common modal verbs that work this way include:

• können = can
• müssen = must
• dürfen = may / be allowed to
• sollen = should / be supposed to
• wollen = want
• mögen / möchte = like / would like

Yes, vorbestellen is written as one word, and it is a separable verb.

The prefix is vor-, and the base verb is bestellen. When the verb is used on its own as the main conjugated verb, the prefix usually separates:

• Ich bestelle das T-Shirt vor.

But when the verb stays in the infinitive because of a modal verb, it does not split:

• Ich will das T-Shirt vorbestellen.

So both are correct, depending on the structure.

Because T-Shirt is a neuter noun in German, so its basic article is das.

In this sentence, das T-Shirt is also the direct object, so it is in the accusative case. For neuter nouns, the nominative and accusative definite article are both das, so there is no visible change here.

Compare:

• nominative: das T-Shirt ist teuer
• accusative: ich kaufe das T-Shirt

So in Ich will das T-Shirt vorbestellen, das is correct because T-Shirt is neuter and is the object.

It is grammatical and natural, but it can sound stronger or more direct than English I want ... sometimes does.

Depending on the situation:

• Ich will das T-Shirt vorbestellen. = strong, direct, determined
• Ich möchte das T-Shirt vorbestellen. = more polite, softer, more like I’d like to pre-order the T-shirt

So if you are talking to a salesperson or writing customer service, möchte is often the more polite choice. If you are just stating your intention casually, will can be fine.

Because all nouns are capitalized in German.

So even though T-Shirt is an English loanword, in German it is still a noun, and nouns begin with a capital letter:

• das T-Shirt
• der Pullover
• die Hose

The hyphen is also normal here; German keeps the standard spelling T-Shirt.

Yes, if you mean a T-shirt in a general or non-specific sense.

Compare:

• Ich will ein T-Shirt vorbestellen. = I want to pre-order a T-shirt.
• Ich will das T-Shirt vorbestellen. = I want to pre-order the T-shirt.

So das suggests a specific T-shirt, probably one already mentioned or one both speaker and listener know about.

Without the modal verb, vorbestellen becomes the main conjugated verb. Since it is separable, the prefix vor- moves to the end.

So:

• Ich will das T-Shirt vorbestellen. = I want to pre-order the T-shirt.
• Ich bestelle das T-Shirt vor. = I pre-order / am pre-ordering the T-shirt.

This is a very useful pattern to notice:

• with a modal verb: infinitive stays together at the end
• without a modal verb: the separable prefix splits off

The ch in ich is pronounced with the soft ich-Laut, a sound English does not really have.

A rough approximation is something like:

• ikh but much softer and more forward in the mouth

It is not like:

• ick
• itch
• ish

So ich should sound closer to ihch, with a light breathy sound after the vowel. This pronunciation is one of the trickier parts of German for English speakers, so it is very normal if it takes practice.