hi Joelbean. I'm not a professional dance teacher, but I am an experienced well trained dancer (international style) and have helped quite a few beginners and social dance regularly. Some general points I would make first.. There should be no difficulty for an experienced dancer to lead the steps you mention - provided you can have reasonable contact with your partner (which may not be welcome in all cases at social dances). Your message implies that they know you quite well, and i sort of get the feeling that they are 'trained' by you. This should make it much easier. Secondly, as the more experienced dancer when dancing with someone for the first time, you must start with basic figures to assess the lady's capabilities; you must be aware of what the lady is doing and especially which foot she is on, so that you can make appropriate adjustments to keep her happy. This would include 'giving up' what you hoped to do if the lady is obviously not in a position to do it.
On your specific question. On the chasse, you don't mention what the preceding figure might be, or if it's a closed chasse or in promenade position. If it's a whisk or an open telemark, there should be no problem with a promenade chasse because you'd be in a promenade-type position already. Opening a lady to promenade from closed position requires a more subtle body action which needs good contact and of course the lady must recognise the signal, but this can be done without any words. The back lock out of a spin turn is something i wouldn't attempt unless I'd recently taught it to the lady.
Good leading requires at least a reliably maintained frame for the lady to dance in, good and appropriate body action (strong cbmp action to lead a lady outside you for a back lock, for example) and good control of body weight. It also requires a lady with appropriate skills. Only you can assess these as you dance with the lady. I can assure you that well trained dancers can dance reasonably complex groups of figures the first time they dance together.