Toddler blanket:
I would use different textures in squares and would include one or two of lovely cuddly minky: http://minkyfabrics.co.uk
Maisie: I don't know that Janome machine. I have a very good Brother sewing machine; my overlocker & embroidery machine are both Janome. I am still getting used to the embroidery machine ( a special birthday gift!) but the overlocker is fantastic and I am so impressed with the quality!
I think the 525 is lightweight, and I would consider that carefully - it's an advantage or disadvantage depending on what you want.
I would, if convenient, go to the shows: you get a range of machines to try and often special offers: http://www.ichf.co.uk/events_calendar.php
If not, I would go to a good shop, they know the models that last well, and sometimes do a good deal on refurbs.