हमें इसे स्वीकार करना होगा।

Not necessarily, but it is most commonly used for difficult or unavoidable things. You can 'sveekar' an award or a gift, which is positive, but the phrase 'Hamein ise... hoga' usually implies a challenge.

Yes, that is the standard present tense. 'Hamein... hoga' is specifically for 'We must/will have to'.

'Sveekar' is Sanskrit-based and formal. 'Kabool' is Arabic/Urdu-based and often used in religious, poetic, or legal contexts (like a wedding vow).

Yes, it is very professional. It shows that you are acknowledging a situation and are ready to move forward.

You would say: 'मैं इसे स्वीकार करने से इनकार करता हूँ' (Main ise sveekar karne se inkaar karta hoon).

Because the verb construction 'karna hoga' requires the subject to be in the oblique case with the postposition 'ko'. Hum + ko = Hamein.

In this specific construction, it functions more like 'must' or 'have to' in the sense of a logical necessity.

Usually, apps use 'Sveekar karein' (Accept) or 'Manzoor karein'. In conversation, you'd just say 'Accept kar liya'.

'Sveekar' is a noun (acceptance). When combined with 'karna' (to do), it becomes a compound verb.

Yes, Hindi speakers across India use this. In South India, the local languages have their own equivalents, but this Hindi phrase is understood in all formal contexts.