You can get 500-1000 leads from a well promoted webinar. Your best bet is probably going to be to partner with some industry organization or publication that will promote your webinar to their lists, budget a grand or two for that, depending on the organization, size of list, etc.
If you get 1/4 of the registrants to actually attend the webinar, that is a good turnout. Either way, you get the leads from the webinar registrants.
You can go with a sales slant, or a technology slant, or anything else you want. Just make sure the webinar description matches the content, and you deliver on the topic. Don't promote a webinar for "Solving PTZ Maintenance Problems" and then just talk about your new PTZ that doesn't really "solve" problems in the general sense. Instead call it something like "Learn How Our PTZ Reduces Maintenance Costs" (this is just an example, I have no idea what you are selling). If people show up expecting to hear about a technology topic and they just get a sales pitch you will have done yourself a disservice by attracting the wrong audience. There are *plenty* of people that will sign up and attend for a sales pitch/new product, if that is your goal, be upfront about it.
Budget for an hour, plan 45-50 minutes of content, and the balance for short intro time and Q&A at the end. 20-30 slides is about right. Make sure you have a good mic/headset and do some run throughs to make sure you get the right tempo to your presentation to keep people listening and engaged. Have a few seed questions for the moderators to ask you if you don't get audience questions right away.