tiomluasocein wrote:
I agree about using the future.
Okay, really in the sense of "Do you want me to do something (for you)" ?
Searching for examples I found e.g.
T. Ó Maille: An dtabharfaidh mé bainne ar a aghaidh don pháiste? = Shall/should I give the child pure milk?
P. Ó Siadhail: An dtabharfaidh mé cuireadh d'Oscar an suíochán deireanach a líonadh? = Shall I invite Oscar to fill the last place?
L. Prút: An mbainfidh mé triail as an gcnaipe seo? = Shall I try this button?
Is this original Irish, a loan translation of English or just a coincidence?
(I read somewhere that "Will I?" was used in Hiberno-English though it should have been "Shall I" in Standard English, prob. due to Irish influence.)
At least it is something unexplained, probably because it is too similar to English.
(English or Irish based) grammar books and dictionaries tend to explain only things different in both languages. But unfortunately, a lot is similar.

In German "Soll ich ..." isn't future tense at all.
tiomluasocein wrote:
But just to complicate things

how about
An mbeadh sé go maith . . .? as a possible alternate?
viz. An mbeadh sé go maith an fhuinneog a oscailt? (?)An mbeadh sé go maith a osclaím an fhuinneog?
They grammar may be shaky, especially the second sentence. Would the subjunctive be used for the main verb "oscail"? > "go n-osclaí mé"
Hmm,

. If so, only "an fhuinneog a oscailt" (or: "má osclaíonn mé an fhuinneog", b'fhéidir)
"an mbeadh sé go maith go ..." doesn't work, I'd think.