Will keep the same permalink structure for avoiding any issues. Keeping permalink structure same as the old site will not affect traffic from search engines and SERP results.
Changing permalink to new structure is also possible without any problems or doing so will not affect traffic from search engines and SERP results. In cage of custom domain in Blogger, old urls will be redirected to the the new urls.
Changing permalink structure is highly recommended for branding your site.
All photos will be there in your new WordPress site.
Access to your Blogger blog and WordPress dashboard.