Learn Spanish (Latin America): Sin embargo, mañana habrá más avispas aquí. - However, tomorrow there will be more wasps here.

Even though más avispas (more wasps) is plural, the verb haber (when used to mean 'there is' or 'there are') is impersonal. Because impersonal verbs don't have a subject to agree with, standard Spanish requires them to stay in the third-person singular. You will occasionally hear native speakers say habrán, but the standard rule is to always use habrá.

Could I use the phrase va a haber instead of habrá here?

Absolutely! In everyday Latin American Spanish, using the structure va a haber (there is going to be) is very common. Just remember that the invariant rule still applies: it must be va a haber (singular) and never van a haber (plural), even with the plural object avispas.

Does the phrase sin embargo literally translate to 'without embargo'?

Historically, yes. The noun embargo originally referred to an obstacle or hindrance. Saying sin embargo meant 'without obstacle,' which eventually evolved into the modern translation 'however' or 'nevertheless.' Today, it functions entirely as a fixed transitional phrase.

Is the word order strictly set, or could aquí go somewhere else?