How to use this without being difficult
None of these questions are hostile, and a good forwarder will be pleased you asked. They spend most of their time with clients who ask nothing and then are surprised, which is worse for everybody.
Send them in one email, before you commit. Not one at a time over three weeks. One list, one reply, and you have a written record of what was promised.
Ask for written answers. Not because you distrust anybody, but because the person you spoke to may be on leave in six weeks when it matters.
Do not negotiate on price until these are answered. A cheaper quotation that excludes four things is not cheaper, and you cannot see that until you know what is excluded.
What the reaction tells you
Watch how the questions are received more than how they are answered. A forwarder who answers quickly and specifically has done this before. One who is irritated, or who answers a different question, is telling you something you will otherwise learn later and more expensively.
The four answers that should worry you
"It covers everything." Nothing covers everything. This means either they have not thought about it or they do not want to say.
"Validity: five to seven days." That is a lead time, not a validity date. It appears on real quotations constantly and it means the price can change without either of you having agreed anything.
"Insurance is recommended." Recommended by whom, at what cover, at what price? An offer that is never actually made is not an offer, and after a loss it becomes your omission rather than theirs.
Silence on duty. If a quotation does not say whether import duty is included, the person paying assumes it is. That is not unreasonable of them, it is what silence means in a price.
The one question worth more than the rest
"Which certificates must be obtained in the exporting country before loading?" Nearly every genuinely stuck shipment is stuck on the answer to that question, asked too late.