You can't specify "professionals" because it implies you will only accept tenants who have jobs, and it's illegal to discriminate against tenants on HAP or rent supplement. Similarly, asking for work references could be potentially problematic; while it's not illegal to ask, it would be illegal to refuse to rent to someone on the basis that they were in receipt of rent supplement or HAP, so if you were to request that and the potential tenant couldn't provide it, or what they did provide indicates they weren't making much money, and so you declined to rent to them, they might have a basis for a discrimination complaint. Threshold have some further information
on the grounds on which you cannot discriminate when seeking a tenant.
If you are requesting copies of those documents from prospective tenants, be careful that you are fully complying with data protection regulations. The Data Protection Commission has some advice on the matter for landlords
. Requesting all of those documents from every potential tenant who inquires about your property would most likely be a compliance violation, but collecting such information from your preferred candidate before making the final decision to enter into a tenancy agreement could be permitted.
Tenants who smoke and tenants with pets are not protected classes and you are free to prohibit either in your tenancy agreement and say as much in your listings. Just make certain that such prohibitions are clearly spelled out in your written tenancy agreement; just verbally telling a tenant about those rules will make them difficult or impossible to enforce if the written agreement is silent about them.