Questions & Answers about Я закажу чай без сахара и буду ждать друга у окна.
Закажу is the perfective verb заказать in the simple future (1st person singular). Perfective verbs form future with a single word (закажу, закажешь, закажет...) and usually mean a completed, single action (placing an order once).
Заказываю is imperfective present and can sometimes mean a near-future plan in conversation, but here закажу is the standard, clear choice.
Ждать is imperfective, so its future is made with быть + infinitive: буду ждать. This emphasizes an ongoing process (waiting for some time).
A one-word future like подожду (perfective) would sound more like wait for a while / wait a bit / finish the waiting, which can change the nuance.
With ждать, Russian most often uses the genitive: ждать кого? чего? → ждать друга, ждать поезда.
Accusative is possible in some contexts (often when the object is very definite/expected), but genitive is the default taught and widely used, especially in neutral sentences like this.