In an ideal world, these are mostly reasonable questions, even if a bit specific to the OP's requirements, but unless you are purchasing SaaS software on a large, enterprise-style license (i.e., 6 figures or more), it probably won't be cost-effective for most vendors to gather and collate this documentation, as well as answering these questions, just like it's not worth it to ink a custom contract on a smaller deal, where legal fees alone might eat up the entire profit margin or even push it negative. Engineering time is expensive and some of these questions are technical or "special" in nature.

There's a reason why standardized third-party audits like SOC-2's and ISO-27001's exist: to reduce the time required to document your veracity and security as a vendor for a potential customer. Since even large customers rely on the statements (independently audited, unlike in these questions) of a security attestation to make purchases, why should a customer request that extra time should be taken away from other responsibilities, like making better products or providing customer support?

I freely admit that I'm a bit biased against ad hoc security questions, even though I used to do it myself when working on large security teams. ;) My security-focused SSH key management company, https://userify.com, went through the time and expense to achieve AICPA SOC-2 certification from an independent third-party auditor to reduce the time and costs involved in responding to smaller RFP's, and to provide fully documented, standardized, and legally binding proof of our security bonafides. We still try our best to intelligently respond to any and all questions, especially about security, from any customers at all, even free-tier customers and hobbyists, but it's harder to do that when presented with a big list of questions that are mostly answered in our SOC-2 audit already.