This is correct if somewhat archaic grammar, "find" meaning "see" -- the one extra word is the repeated "please" on the second independent clause, which results from combining two sentences.
In modern English, one might say "Please see the attached photos of my paintings, on which I would appreciate your feedback."
No this is not correct use of kindly
It should be "Please find attached my husband's insurance card".
Please find attached my repairing offer confirmation.
Almost but not quite. The grammatically correct wording is "Please see the attached agenda." As a shorthand, you could also say "Please see agenda (attached)."
Please find attached the leave schedule of all staff for the holiday
Yes, the grammar in the sentence "The attached invoices have been confirmed" is correct.
No this is not correct use of kindly
It would be grammatically correct to say: Please find the attached.... it does not make much sense to write both kindly and please since both almost mean the same.
Please find attached my repairing offer confirmation.
It should be "Please find attached my husband's insurance card".
Almost but not quite. The grammatically correct wording is "Please see the attached agenda." As a shorthand, you could also say "Please see agenda (attached)."
Please find attached the leave schedule of all staff for the holiday
transffered complete
No, "will be had" is not a correct grammar. The correct grammar would be "will have."
The grammar in your sentence is mostly correct, but there are minor adjustments needed for clarity and punctuation. It should read: "Please find attached a Preliminary Invoice for your reference. Be aware that this is not a final invoice." Removing "an" before "attached" improves the flow, and there should be no space before the period after "invoice."
No, it is correct grammar, not a correct grammar.
The correct grammar is: "Are those correct?"